The Blackett Laboratory

Department of Physics Review

Faculty of Physical Sciences 2002

Introduction

This has been a year of progress and achievement in the A number of major projects were initiated in the department, department. It continues to flourish and to be an exciting including a Basic Technology programme grant on the place to study and work. We continue to attract a large generation and application of attosecond light pulses and cohort of the cleverest young people into Physics, and to a DTI Beacon Award to Professor Paul French to develop give them a challenging education that they and the fluorescent lifetime image technology for biomedical external world value highly. We have not rested on our applications. The departmentÕs contribution to e-Science laurels: the degree programmes have undergone an and the GRID has continued to flourish. extensive revision this year and a new MSci programme in Theoretical Physics introduced. And its still a fun Members of the academic staff garnered a number of place to be! The undergraduate body has been very important awards and prizes during the year, reflecting successful in winning awards this past year: the Imperial the high standing they are held in by the outside world. College Physical Society won the Institute of Physics Professor Gareth Parry was elected as a fellow of the award for the best Physics Society in UK Universities. Royal Academy of Engineering. Professor Arkady Tseytlin Students in the department were very successful in the was awarded a Royal Society Wolfson Merit Award, a College Entrepreneurship Ideas Challenge, and a highly prestigious award intended to retain research stars in physics team won the top £25,000 prize. the UK. Dr Ralf Toumi was awarded the £50,000 Philip Leverhulme Prize in recognition of his research in atmos- The department continued to work with outside bodies in pheric physics. A team from the Physics and Computer valuable research collaborations. New links with BP, with Science Departments won top prize in the Supercomputer the Culham Laboratory and with the Sandia National 2002 Conference in the USA for their project on real-time Laboratories in the USA have been established, and the genome sequence to gene function analysis. Professor College has signed a Memorandum of Understanding Peter Cargill was awarded a PPARC Senior Fellowship with the National Physical Laboratory that will enhance for 3 years and Dr Almut Beige was awarded the James research collaborations in a number of areas. The newly- Ellis Research Fellowship of the Royal Society to pursue her established Exploitation Committee, under Lesley CohenÕs work on quantum computing and quantum cryptography. leadership, is exploring ways in which the departmental Intellectual Property can be better used. To end on a sad note, I am sorry to say that Professor Tony Stradling died a few weeks after his retirement from A number of new staff joined us this year: we welcome the College. A memorial service was held to commemorate Professor Edward Hinds and Dr Ben Sauer who have his life and achievements in Oxford Cathedral, attended by joined the QOLS Group from the University of Sussex to many present and past members of the department who establish the Imperial College Centre for Cold Matter. Dr remember an outstanding colleague with great affection. Paul Nandra joined the Astrophysics Group from the Goddard Space Science Center in the USA. Dr Mark P. L. Knight FRS Neil and Dr Peter Torok joined the Photonics Group from Head of Department Oxford University. April 2003

The major refurbishment of research laboratories under the GovernmentÕs SRIF programme has delivered high quality space for new programmes. We have become used to having an army of contractors working in the place and this will continue for the coming year, but will result in laboratories more fitting for the 21st century.

The cover: The images on the cover, which were obtained in December 2002, show the first ever measurement of the EarthÕs energy budget from a geostationary satellite, EuropeÕs first Meteosat Second Generation (MSG-1). The upper image is a measurement of the thermal energy emitted from the Earth and the lower image shows the amount of sunlight reflected by the clouds and the EarthÕs surface. The satellite is positioned over 0¡ latitude and 0¡ longitude, so that in the lower image we see Africa to the right, and South America to the left. These data were obtained by the Geostationary Earth Radiation Budget (GERB) instrument on MSG-1. GERB is a joint European project led scientifically by Imperial College London. Being in a geostationary orbit, GERB remains located over the Greenwich meridian and the Equator and is able to obtain images, like those shown here, every 15 minutes, which is much more frequently than has ever been possible before. These data are currently being used by researchers within Imperial College London and around the world to provide new insights into climate processes such as clouds and convective systems, and to improve the climate models used to investigate the future of the EarthÕs climate. (For more information, see the annual report of the Space and Atmospheric Physics Group, pages 31-33). 1 Condensed Matter Theory Head of Group: Professor Experimental D D Vvedensky Solid State Astrophysics Page 7 Physics and Centre Head of Group: for Electronic Materials Professor and Devices M Rowan-Robinson Head of Group: High Energy Professor D Bradley Page 4 Physics Page 10 Head of Group: Professor P J Dornan Optics Optics Photonics Laser Consortium Page 16 Head of Group: Director: Professor P M W French Professor J P Marangos Plasma Physics Page 22 Page 19 Head of Group: Professor S C Cowley Optics Page 25 Quantum Optics Space and and Laser Science Atmospheric Physics Head of Group: Head of Group: Professor G H C New Professor J E Harries Page 28 Theoretical Physics Page 31 Head of Group: Professor K Stelle

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For contact addresses see page 49

2 The Blackett Laboratory http://www.imperial.ac.uk/physics

General Departmental Information Head of Department Associate Head of Department Professor P. L. Knight FRS Professor R. W. Smith Tel: 020 7594 7500 Tel: 020 7594 7501 Fax: 020 7594 7504 Fax: 020 7594 7504 e-mail: [email protected] e-mail: [email protected]

Director of Facilities Director of Undergraduate Studies Dr. R. G. Burns Professor A. R. Bell Tel: 020 7594 7700 Tel: 020 7594 7505 Fax: 020 7594 7777 Fax: 020 7594 7509 e-mail: [email protected] e-mail: [email protected]

Senior Tutor (Undergraduates) : Director of Postgraduate Studies Dr R. J. Forsyth Dr J. Sedgbeer Tel: 020 7594 7524 Tel: 020 794 7512 Fax: 020 7594 7509 Fax: 020 794 7509 e-mail: [email protected] e-mail: [email protected]

Admissions Tutor (Undergraduates) : Schools Liaison Officer Professor W. G. Jones Dr J. Hassard Tel: 020 7594 7513 Tel: 020 7594 7792 Fax: 020 7594 7509 Fax: 020 7823 8830 e-mail: [email protected] e-mail: [email protected]

Undergraduate and Postgraduate Studies Undergraduate Teaching Page 37 (Queries about undergraduate admissions should be addressed to the Admissions Tutor)

Schools Liaison http://www.imperial.ac.uk/options/ Page 40

Postgraduate Studies - Page 41

MSc Prospective postgraduate students interested in admission for an MSc course should contact the appropriate course organiser listed below. MSc in Optics and Photonics Dr. K. Weir, Tel: 020 7594 7723, Fax: 020 7594 7714, e-mail: [email protected] MSc in Quantum Fields and Fundamental Forces Dr. J. Halliwell, Tel: 020 7594 7831, Fax: 020 7594 7844, e-mail: [email protected]

PhD Those interested in admission for doctoral level research leading to the PhD degree should contact the Heads of Research Groups in subject areas of interest as listed opposite. The Director of Postgraduate Studies will be glad to advise on all general matters concerning the requirements for admission as a postgraduate student.

3 Astrophysics http://www.imperial.ac.uk/research/astro

Head of Group: Professor M. Rowan-Robinson

Experimental Astrophysics

T. J. Sumner, W. G. Jones (HEP), I. Liubarsky, J.J. Quenby, G.K. Rochester, H. Araujo, A. Bewick, D. Davidge, A.S. Howard (HEP), V. Lebedenko, R. Luscher, D. Shaul, C.G-Y. Lee (SPAT), and T. Ferbel (visitor)

Search for Dark Matter Particles Figure 2. Inertial Sensor design work for LISA. On the left is a rendered view of the Parts manufacture for ZEPLIN III, our engineering model of the Charge Management System for SMART-2, being next generation two-phase xenon developed under contract to ESA. On the right is the new estimate of mean charging detector for dark matter search, is now rates for the proof-masses from cosmic-ray protons and alpha particles. These rates 80% complete. This will be used to are higher than previously estimated, but still within the capabilities of the charge search for signatures of direct inter- management system to control. actions of exotic new particles in the Gravitational Wave Astronomy Gravitational wave astronomy from Boulby underground facility. The detailed design of the Charge space was highlighted as a high Meanwhile the UKDMC collaboration Management System for the SMART- priority area for PPARC funding in has deployed a simpler single phase 2 technology precursor satellite to the recent Government spending liquid xenon scintillation target, gravitational wave science mission, review. ZEPLIN I. This uses a pulse shape LISA, of the European Space Agency discrimination technique, and, after is complete (Figure 2). Neutrino Astrophysics only a few weeks operation, has We are developing an Engineering The Astrophysics Group has formally produced the best results in the world Model of the system. This system is been accepted into the AMANDA (Figure 1). These new results now cast required by LISA to control the charge and ICECUBE collaborations. Our very serious doubt on earlier claims build-up on the isolated proof-masses, scientific interest is in the connection by a group based in Rome to have which form the mirrors for the large between neutrino emission and gravi- detected the dark matter particles at baseline interferometry between the tational waves, which would be higher interaction strengths (green three spacecraft in the constellation. expected in some of the more contour in the figure). Our new results Charge build-up is caused by cosmic- extreme forms of collapse/explosion are an upper limit and the dark matter ray impacts on the spacecraft and of astrophysical objects. particles must be below it. ZEPLIN proof masses. New analyses of the way III should achieve about 2 orders of in which the charge is deposited, using Studies of Stars and Supernovae magnitude better sensitivity within a the latest version of GEANT4 have few years and this will maintain our shown that this effect may be more J. E. Drew, W. P. S. Meikle, L. Lucy, world leading position, and pave the severe than previously thought, and a Y. Unruh, R. Kotak, M. Pozzo, way for larger targets with up to 1 new contract has just been agreed S. Sim, and J. Vink tonne of xenon. with ESA to continue this work. Young stars The problem of how the late accretion phase of young stars depends on stellar mass continues to be explored using high resolution spectropolarimetry Ð a technique that provides insight into the geometry of the circumstellar environment on scales significantly smaller than direct imaging can reach. This year, a study of the intermediate- mass Herbig stars was completed and published. We found a marked Figure 1. The left-hand panel shows the current results from the worldÕs most change in the character of the linear sensitive particle dark matter searches. The new result from our collaboration with polarization observed across Ha (a RAL and Sheffield University is the lowest (best) curve labelled ÔZEPLIN IÕ. The right- bright hydrogen emission line) between hand panel shows some parts from ZEPLIN III made out of pure copper. the generally cooler, lower-mass 4 Herbig Ae stars and hotter, higher- the ejecta of the core-collapse SN Ha emission line stars We have mass Herbig B stars. Our result 1998S, strengthening the belief that established and are the UK lead in a reinforces already suspected similar- supernovae are major sources of long-term collaboration to carry out ities between Herbig Ae stars and interstellar grains. However, some a deep spectroscopic survey of the the lower mass young stars dust may also have formed in the southern Galactic Plane for Ha commonly known as TTau stars. progenitor wind. We continued our emission line stars. The high sensi- This finding has been followed up IR observational programme aimed tivity of the imaging provided by the with the first high-resolution linear at detecting core-collapse super- now-complete AAO Schmidt Ha spectropolarimetry of TTau stars. novae in the dusty nuclear regions imaging survey (See Figure 3) picks of starburst galaxies. One candidate out candidate emission line objects We also work on Doppler reconstructive supernova has already been found. down to a faintness limit that promises imaging of the surfaces of TTau stars See a factor of 100 expansion of existing using high resolution spectroscopic http://astro.ic.ac.uk/Research/Stellar/ catalogues of emission line stars. time series. TTau stars are complex Supernovae/NSN/images.html. This is an important opportunity objects: the mass accreted from their because Ha emission is a marker circumstellar disks onto the stellar Thermonuclear Supernovae Our for just those late and early stellar surface via magnetic loops. The investigations of thermonuclear evolutionary stages that remain poorly indirect imaging aims to better (type Ia) supernovae via early-time understood Ð mainly because so few understand the accretion and the spectroscopy continued under the examples of key object types are yet role of magnetic fields in such stars. umbrella of the Type Ia Supernovae known. Surface images obtained of the TTau EU Research Training Network. We star, SU Aurigae, show that features are one of the two main observa- Numerical modelling Activity has can change on very short time tional groups involved. Late-time centred on developing numerical scales (roughly one rotation period) spectroscopic work also continued radiation transfer techniques. and that variability is present that with the completion of our first multi- Previous work on transition probabil- cannot be explained as due to either zoned spectral model for type Ia ities for Monte Carlo energy packets cool or hot star spots. This suggests supernovae. Our joint programme has been extended to treat interac- Doppler images of TTau stars derived with Liverpool John Moores University tions with the thermal pool of free (as is commonly done) from line made good progress with the electrons. This then allows the Ômacro- profiles observed over several completion of the SupIRCam atomÕ statistical sampling formalism rotation periods should be treated infrared camera for the new robotic to be used to obtain NLTE solutions with extreme caution. Liverpool Telescope. Observations for stratified atmospheres. In parallel, with it, starting in 2003, will test for we are developing an algorithm using The Sun as a star Knowledge of systematic bias (due to intervening these techniques that is designed to long-term variations of the solar dust) in the use of Type Ia super- facilitate generalisation to multi- brightness is an important input to novae as cosmological distance dimensional media. These develop- studies of the EarthÕs climate change, indicators. ments will enable realistic modelling especially when trying to isolate of the spectra of a wide range of man-made contributions. We have astrophysical environments. taken an important step towards accurate modelling of solar variability, Cosmology and Extragalactic by showing that brightness changes Astrophysics between solar cycle minimum and maximum can be attributed solely to M. Rowan-Robinson, S. Warren, changes in the surface coverage of A. Jaffe, K. Nandra, M. Graham, dark and bright magnetic elements. M. Fox, S. Dye, L. Mendes, R. Priddey, We have started to apply our knowledge D. Clements, C. Pearson, D. Rosa, of solar variability to other Sun-like and T. Takagi stars within the framework of the Corot asteroseismology and planet- Infrared and submillimeter surveys finding mission. With collaborators at Edinburgh, Cardiff and Durham, the Group has Core-collapse Supernovae In our embarked on a new survey of 0.5 study of SN 1987A we concluded square degrees of the sky (SHADES) that the dramatic slowdown in the Figure 3. Star fields and Ha nebulosity in at 850 microns with the James Clerk decline of forbidden lines indicates Vela - field 459 from the AAO UK Schmidt Maxwell Telescope (JCMT). Results Ha Southern Galactic Plane Survey that excitation of the ejecta at very from their earlier survey of 200 square (http://wwwwfau.roe.ac.uk/sss/halpha/in late times is driven by the radioactive arcminutes of sky were published 44 dex.html). This is just one of the 234 4¡ decay of Ti. We obtained strong x 4¡ fields imaged, available for spectro- during the year, demonstrating that evidence for dust condensation in scopic follow-up. most submillimetre sources are high 5 redshift star-forming galaxies. The galaxies are surprisingly strongly clustered. The Group has also carried out a study, using data from the Hubble Space Telescope, of host galaxies for high redshift supernovae. Several of the galaxies appear to be undergoing interactions and seem similar to the star-forming galaxies found in infrared surveys. A search for dust in these galaxies has been started using the JCMT.

Preparations have continued for the SWIRE Legacy Survey to be carried out with NASAÕs Space Infrared Telescope Facility (SIRTF), due for launch in April 2003. This is the largest survey project being carried out by SIRTF and is expected to yield over a million infrared galaxies, in the wavelength range 3 to 170 microns. Rowan-Robinson (Deputy PI) leads the SWIRE science Figure 4. Semi-linear inversion of the gravitational lens system 0047-2808. Upper L, program. HST image 5 arcsec x 5 arcsec showing a galaxy (redshift z=0.5) that has lensed a background galaxy (redshift z=3.6) into a ring; upper R, same after subtraction of the With collaborators at Kent, Sussex image of the lens galaxy; lower L, reconstructed source light profile over 1 arcsec x 1 and Groningen, the group is preparing arcsec, showing it is double (note smaller scale); lower R, reconstructed model ring image. the data analysis pipeline for the Japanese all sky far infrared survey of the sun) in the centres of galaxies. X-ray astrophysics We have used mission, ASTRO-F, due for launch in With Don Backer, we have published observations with the Chandra x-ray March 2004. The group leads the a study showing that such gravitational observatory of Lyman-break galaxies Framework 5 EC TMR Network, radiation may be detectable using in the Hubble Deep Field North, to ÔProbing the Origin of the Extragalactic observations of millisecond pulsars, provide the first x-ray constraints on background radiation (POE)Õ more accurate than any terrestrial star formation at high redshift. The involving 20 European groups. clocks. This work involves calculations results are in remarkable agreement of the formation of galaxies, the with UV measures, and indicate that Cosmology The Astrophysics Group, dynamics of the black holes, and the future, deeper views of the x-ray continues its involvement in the detection of gravitational radiation. universe will be dominated by MAXIMA and BOOMERANG experi- starforming galaxies. We have also ments, measuring the anisotropy of Gravitational Lensing We have completed the analysis of a new, the cosmic microwave background developed a new method for the large-area hard x-ray survey with the (CMB) radiation. The BOOMERANG inversion of images of gravitational ASCA satellite. The results shed consortium completed the final lenses, that is faster and more new light on the nature of obscured analysis of the anisotropy power accurate than previous methods. A AGN, and, in particular, bring into spectrum, and the measurement of galaxy or galaxy cluster can act like question the applicability of standard cosmological parameters, from the a lens, distorting and magnifying the AGN synthesis models. current data. MAXIMA data were image of the source galaxy. As illus- used to observe and characterise trated in Figure 4, the Ôsemi-linearÕ emission from intervening astro- inversion method solves simultane- physical sources of microwaves, ously for the light profile of the both in the Milky Way and in distant source, and the mass density profile galaxies. Both teams have also begun in the lens, that recreates the image to prepare for new data observing seen. The method is now being the polarisation of the CMB radiation. applied to Hubble Space Telescope images of lens systems to investigate We are also involved in an ongoing the dark matter profiles in galaxies project to determine the gravitational and galaxy clusters. radiation from super-massive black holes (up to a billion times the mass 6 Condensed Matter Theory http://www.imperial.ac.uk/research/cmth

Head of Group: Professor D. D. Vvedensky Science of Complexity K. Christensen

The science of complex systems is highly interdisciplinary. It deals with dynamical systems composed of many interacting parts. Methods from statistical mechanics are employed to gain insight into the behaviour of such systems. The overall objective is to address why nature is complex, not simple, as the laws of physics seem to imply. Rain is Earthquakes in the Sky K. Christensen and O. B. Peters

We demonstrate how, from the point of view of energy flow through an open system, rain is analogous to many Figure 1. The exchange-correlation hole about an electron (the white dot) in a model other relaxational processes in Nature many-electron system. The left-hand figure shows the hole calculated using an such as earthquakes. By identifying accurate quantum Monte Carlo method; the wavy ribbon shows the electron density; rain events as the basic entities of and the right-hand figure shows the simple spherical form assumed in the local the phenomenon, we show that the density approximation. number density of rain events per interatomic forces, which cannot be a new and sophisticated treatment of year is inversely proportional to the understood using classical physics finite-size errors, of the surface energy released water column raised to the alone. To simulate chemical reactions of the uniform electron gas, the value power 1.4. This is the rain-equivalent accurately, it is necessary to use of which has been the subject of a of the Gutenberg-Richter law for quantum mechanics. Most quantum long standing controversy. A precise earthquakes. The waiting times between mechanical simulations replace the calculation of the surface energy as events is also characterised by a scaling electron-electron interactions by a a function of density will provide an region, where no typical time scale simple effective potential or mean field. important benchmark for other theories exists. This is the rain-equivalent of The simplest approximation of this and serve as a stepping stone towards the Omori Law for earthquakes. All type, the local density approximation, simulations of more realistic surfaces. of our findings are consistent with the assumes that the exchange-correlation Our second project is to calculate concept of self-organised criticality, hole surrounding each electron is the exchange energy densities in a wide which refers to the tendency of slowly same as in a uniform electron gas. range of many-electron systems. driven non-equilibrium systems As can be seen from Figure 1, this This will allow us to test existing towards a state of scale free behaviour. is not a good assumption. Other approximations and, we hope, mean-field approximations are derive better ones for use in density- The Quantum Mechanics of somewhat more realistic, but they functional calculations. Electrons in Solids have not proved accurate enough to Quantum Phases of Matter study chemical reactions reliably W. M. C. Foulkes, B. Wood, and and consistently. D. K. K. Lee A. S. Khorashad The Quantum Monte Carlo (QMC) When we put together a large collection The de Broglie waves associated methods we use, which solve the of atoms or electrons, order may with the electrons in molecules and full Schršdinger equation including emerge from their complex cooper- solids scatter from the atoms and electron-electron interactions, are at ative behaviour. A central challenge interfere, enhancing the electron least an order of magnitude better. in condensed matter physics is the density in some places and reducing This year we are focussing on two question: "how does the sum become it in others. This quantum mechanical main projects. The first is to carry more than its parts?" Theoretical effect plays an important role in out QMC simulations, incorporating progress in understanding such chemical bonding and contributes to 7 "emergent phenomena" can help us of a simple classical machine become search for, and even design, new very small. We have studied a system materials of practical importance. of gears and derived the quantisation Examples include superconductivity rules for the states of such a system. and ferromagnetism. The question is Disordered Systems how these exotic phases of matter might emerge from the interplay of J. M. Carter and A. MacKinnon quantum interference, strong interac- tions and disorder. Cuprate supercon- We have developed a transfer matrix ductors have caused much excitement like method for 1D disordered inter- in the last decade because they do not acting systems. Spinless fermions have to be cooled to extremely low show a metal-insulator transition for temperatures to become supercon- attractive interactions, in contrast to Figure 2. An Aharonov-Bohm ring with a ducting. Strangely, they are far from quantum dot on one arm. Close to the non-interacting systems for which all ordinary metals even in the resistive dot is a charge on the end of a spring or states are localised in both 1 and 2 state at room temperature. I have been cantilever. The charged spring may be dimensions. The method can be working on a gauge theory of this viewed as a detector which can change extended to other models and to strongly correlated quantum system. state if an electron goes round the right systems of finite cross-section; an A key prediction of our picture on the side of the ring. The arrows indicate 2 essential first step to studying 2 and optical properties of the cuprates has wave paths which interfere at the dot. 3 dimensional systems. recently been tested in experiments - of a dot on a spring or cantilever Spintronics and Semiconductor - our results are consistent with the which can move between 2 contacts. Systems experimental findings. Decoherence Transport can occur either by resonant in quantum Hall ferromagnets consists tunnelling or by shuttling, where one A. Oliveira, E. A. Johnson MBE, and of two parallel two-dimensional electron per cycle is carried from one A. MacKinnon electron gases in a strong magnetic contact to the other. If the potential field. These layers are in close difference across the system is larger Due to the increased interest in proximity on the atomic scale in a than the oscillation frequency the spintronics, the use of a spin GaAs hetero-structure. The cantilever may be driven by excitation polarised current, much effort has Coulomb interaction between the by the electrons themselves. The been expended in the design of electrons in the two layers drives a behaviour is very sensitive to the devices which can produce such a quantum transition to an ordered mechanism for dissipation of the current. While many of these use state, akin to a ferromagnet (where all mechanical energy: something which magnetic materials, some designs the magnetic moments point in the is badly understood. An Aharonov- make use of the Rashba effect same direction). A simple theory would Bohm ring is a realisation of Young's which associates a splitting of the predict coherent charge oscillations slits for electrons in a solid. degeneracy of the spin states with between the layers, but this is not Quantum mechanics textbooks the built in electric field in an observed. We are the first to attempt typically state that any attempt to asymmetric structure. While studying a microscopic account of decoherence detect which of 2 paths is taken by an the electronic properties of the in this system, which we believe is electron will result in the destruction unusual semiconductor junction the key to this puzzle. From a wider of the interference processes. We GaSb:InAs we noted an unexpectedly perspective, this system provides a have considered a system consisting large spin splitting in symmetric testbed for ideas about decoherence of an Aharonov-Bohm ring coupled quantum wells. We have now been in materials which exhibit quantum to a charged cantilever (see Figure 2). able to show that the lack of inversion order (such as superconductors and symmetry in the structure of these ferromagnets). Understanding In a simple picture the state of the materials and the strong spin-orbit decoherence is crucial to fulfilling cantilever can only be changed if an coupling in such heavy atoms the promise of these systems as electron goes round its side of the suffices for the spin-splitting and that candidates for nanotechnological ring; the interference fringes should the asymmetric device structure is applications. then be destroyed. Surprisingly this unnecessary. is not the case: the state of the NEMS - Nanoscopic Materials for Near Field Optics cantilever can change while preserving Electromechanical Systems the interference. It appears therefore J. B. Pendry, S. A. Ramakrishna, A. D. Armour and A. MacKinnon that a fundamental tenet of quantum S. O'Brien and W. Williams mechanics has been broken. We are interested in the mechanical However, the effect can be explained We have continued our work on and electromechanical behaviour of in terms of interference close to the novel optical materials whose systems in which the mechanical cantilever; far from contradicting basic properties depend on the details of degrees of freedom exhibit quantum quantum mechanics it confirms it. their structure. The new class of effects. A quantum shuttle consists What happens when the components material we work with has sub 8 associated with atomistic processes are incorporated within stochastic transition rules of a master equation, while a continuum equation of motion, derived from this master equation, describes the macroscopic evolution of the coarse-grained system.

There are many advantages to representing the dynamics of a lattice system as a partial differential equation, including (i) the vast analytic methodology available for identifying Figure 3. Our new "magnetic wires" transfer the magnetic field from one side of the asymptotic scaling regimes and device to the other. Here we image a magnetic field in the form of an 'M'. performing stability analyses, (ii) the Left: schematic arrangements. Right: experimental results obtained by Mike Wiltshire possibility of extracting the macro- (Imperial) and David Edwards (Oxford). scopic properties of the system by coarse-graining the microscopic wavelength structure and for its Coarse Graining of Driven Lattice equations of motion, and (iii) the fact activity relies on the surface modes Models induced at the interface between that, in general, the qualitative materials with positive and negative A. Chua and D. D. Vvedensky behaviour of a lattice model is more dielectric function, or permeability. readily apparent than from its transition This structure, which may be an a Most phenomena in materials science rules, which helps to establish scale of nanometres, allows us the result from the interplay between connections between different models apply the materials to situations where processes that are operative over a and thereby facilitates the transferral the electromagnetic field structure is wide range of length and time scales. of theoretical concepts and methods on a length scale much shorter than For example, the formation of dislo- across disciplines. the wavelength of light i.e. to the near cations within a material (atomic field. This year we have extended scale) and their mobility across grain We are developing a method for our concept of the perfect lens: a lens boundaries of the microstructure deriving continuum equations of whose resolution is not limited by the ("mesoscopic" scale) affect the motion from the transition rules of wavelength of light. We have shown deformation behaviour of the material lattice growth models. Our procedure that there are several alternative (macroscopic scale). A complete is based on regularizing and coarse designs for the lens, some of which understanding of mechanical properties graining discrete Langevin equations give very much better performance thus requires theoretical and compu- that are obtained from a Kramers- than the original slab of negatively tational tools that range from the Moyal expansion of the master refracting material. A strong feature atomic-scale detail of first principles equation and invoking a limit theorem of our programme is the large number density functional methods to the due to Kurtz. As a test of our of collaborations in which we are more coarse-grained picture provided methodology, we have applied this engaged: several major laboratories by continuum elasticity theory. At approach to several standard driven in the USA funded by a MURI award, this level of discussion, epitaxial lattice models, including the biased and collaborators in Europe funded phenomena are no different from any random walk with exclusion, which by the CEC. We also collaborate other problem in materials science. leads to Burgers equation, and the with several other departments in the deposition and instantaneous relaxation College: Mechanical Engineering on Understanding the morphology and of particles on a lattice to minimise simulation of novel optical materials, properties of epitaxial films requires local height variations, which leads and with the Robert Steiner Magnetic accommodating the atomic-scale to the Edwards-Wilkinson equation. Resonance Unit group at the scale information about the movement Hammersmith. This latter collaboration of adatoms on surfaces and their has led to the design of a 'magnetic various bonding configurations into endoscope' for the RF fields employed the macroscopic evolution of the thin in MRI. Figure 3 shows the endoscope film. The dynamics of such lattice imaging an RF field with a resolution systems are generated by transition of 1cm - three orders of magnitude rules for site occupation numbers greater than the RF wavelength of that are expressed in terms of the 15m. The device exploits a new occupancies of neighboring sites at metamaterial which behave like a the preceding time step. This magnetic wire conducting a magnetic provides the basis for a multiscale field from one side of the sample to approach to nonequilibrium systems the other. in that microscopic fluctuations 9 Experimental Solid State Physics, http://www.imperial.ac.uk/research/exss Centre for Electronic Materials and Devices, and Centre for High Temperature Superconductivity

Head of Group: Our activities are classified into violanthrone and a soluble C60 Professor D.D.C. Bradley three main sections, namely fullerene derivative, PCBM. In each molecular electronic materials and case the molecule acts as electron Our programme of research covers applications, transport and magnetism, acceptor and provides improved most aspects of modern experimental and semiconductor optoelectronics. electron transport. The influence of solid state physics including molecular blend composition and morphology electronic materials, soft condensed Molecular Electronic Materials and has been probed via a wide range of matter, quantum optics and photonics, Applications experimental techniques. Structural magnetism, superconductivity and characterisation has used AFM, X- inorganic semiconductors. There is Dye Sensitised and Organic Solar ray and TEM. Photoluminescence a strong emphasis on novel materials Cells quenching, time-of-flight [TOF] and structures and on applications photocurrent, electroabsorption in a wide range of devices. Selected J. Nelson, C. Olson, A. M. Eppler, spectroscopy, and J-V measurements examples of current interests include D. Poplavskyy, P. Ravirajan, under dark and light conditions were next generation thin film solar cells F. M. Braun, R. Pacios, J. Cabanillas- all used to probe generation and (using inorganic semiconductor Gonzalez and D. D. C. Bradley collection of photocarriers. Film quantum wells, nanostructured oxides morphology, especially in respect of and organic semiconductors), optical Solar cells based on molecular the nature and length scale for microcavities (weak and strong electronic materials rely on charge phase separation, has proven to be coupling structures and their photonic separation at the interface between critical to performance. A range of properties), quantum optics in solids an electron-accepting and electron- pre- and post-deposition film treat- (electromagnetically induced trans- donating material. Light generated ments have thus been used, parency and quantum light sources), excitons are dissociated to yield including thermal annealing and ultrafast photonics for datacommuni- separated charges that travel to the solvent exposure. cations (sources, amplifiers, optical electrodes to yield a photocurrent. routers and switches), quantum dots Structures where the two phases In dye sensitised solar cells (DSSCs), (as novel gain media and for extended interpenetrate to create a large light is absorbed in dye molecules wavelength range light emitting diodes interface area are desirable and we attached to the surface of a (LEDs)), spectroscopic studies of soft are studying a range of such semiconducting TiO2 film. High matter (liquid crystals, biomolecules, 'distributed heterojunctions' based optical density is achieved using polymers), metrology for the life on polymer/polymer and polymer/ porous nanocrystalline films with a sciences (single molecule spectroscopy molecule blends as well as dye huge surface area. Electrons excited and microanalysis systems), spintronic sensitised systems. in the dye are rapidly injected into devices, High Tc and MgB2 super- the semiconductor, while the positive conductors, Si-SiGe electronics (solar Polymer/molecule blends under ÔholeÕ on the dye is removed by a cells and high speed transistors) and study utilise polyarylenevinylenes hole-conducting electrolyte. Because molecular electronic materials and and polyfluorenes blended with the positive and negative charges devices (high efficiency LEDs for displays and lighting, TFTs for plastic electronics, and photodetectors).

The Group is strongly linked to the Centre for Electronic Materials and Devices (CEMD), which was estab- lished in 1998 to promote interdisci- plinary and interdepartmental research in electronic materials and devices. The Centre draws together people from the departments of Physics, Chemistry, Electrical and

Electronic Engineering and Materials Figure 1. Quantum efficiency spectra of ITO/TiO2/F8T2/Au devices with and without into a wide range of interdisciplinary 100 nm of nanocrystalline, porous TiO2 between the dense TiO2 backing layer and projects. the < 100 nm spin cast Dow Chemical Company F8T2 polymer layer. The increased interfacial area enhances photocurrent quantum efficiency by a factor of five. 10 are carried to the cell terminals in and other devices. We have shown characterisation of optical gain and different materials, the probability of that dark injection transients, can be loss properties for polymers with recombination is reduced, and the used to accurately measure the hole emission in the range 400 - 800 nm demands on material quality are mobility in very thin films of conjugated and (ii) the fabrication and charac- much less stringent than for single hole transporting materials, and that terisation of lasers based thereon crystal devices. Power conversion in materials where hole transport is (see Figure 2). efficiencies of around 10% can be non-dispersive, the mobility is Strong coupling in conjugated achieved in this way. We have shown independent of film thickness. This polymer microcavity structures previously that electron recombination result is important for photovoltaic with the dye cation in DSSCs is rate- and light emitting applications, where N. Takada, R. P. F. Oulton, limited by electron transport in the device thicknesses are typically 100 P. Stavrinou and D. D. C. Bradley TiO2 film, and can be controlled by nm. Mobility measurements were varying chemical structure and previously done mainly on ³ 1µm Photoluminescence (PL) and treatment of the interface. Our thickness films using the TOF electroluminescence (EL) from recent research has shown that technique, and the relevance to thin weakly-coupled conjugated polymer recombination with the hole conducting film (² 100 nm) devices was uncertain. microcavities has been investigated material, the main loss mechanism Electroabsorption has also been extensively for LEDs and vertical in these devices, is also normally used to better understand the nature cavity lasers. In this perturbative controlled by electron transport within of interface processes that give rise regime the Fermi golden rule still the TiO2. However, at low hole density to electric fields either adding to or applies and there is a spectral and the diffusion of hole transporting opposing the externally applied bias. spatial redistribution of the emission species may be the limiting step. probability with a resulting, cavity Polymer gain media for optical This is particularly relevant to the resonance determined, spectrally amplifiers and lasers design of solid state DSSCs, where narrowed, non-Lambertian emission. hole mobility is low, and may lead to G. Heliotis, R. Xia, M. Ramon, Recently, however, the non-pertur- resistive losses. We are currently M. Pintani, M. Koeberg and bative strong-coupling regime integrating our findings about charge D. D. C. Bradley between exciton and photon modes transport and recombination into a has also been demonstrated for device model to interpret solar cell Semiconducting (conjugated) polymers organic microcavities containing characteristics. are now attracting considerable materials such as porphyrins and J- attention as a new materials class aggregated cyanine dyes but not for A new experimental topic concerns for use in electronics and optoelec- conjugated polymers which typically photovoltaic applications of composites tronics. In addition to many other have too large linewidths. We sought of nanostructured TiO2 films with applications, including full colour flat to directly address this issue via an conjugated polymers. In this system panel displays, there is increasing initial experimental and theoretical the polymer sensitises the TiO2 film, interest in developing these materials study on microcavities containing s- and high optical density can be as optical gain media for lasers and conjugated poly(bis(p-butylphenyl)silane) achieved with much thinner films than optical amplifiers. In particular, an [PBPS] (see Figure 3). PBPS has for solid state DSSCs. This relaxes important future target is the realisation an exciton binding energy EB Å 500 the demands on conductivity for the of an electrically pumped polymer meV that allows room temperature hole transporter. We have shown solid-state laser diode. We have a study of polariton effects. Silicon that very efficient charge separation programme focussed on (i) detailed backbone polymers of this type also occurs at the interface between TiO2 have the large oscillator strength and and polymer, and that introducing a narrow linewidth that is essential to porous layer between the dense TiO2 observe strong-coupling: PBPSÕ electrode and polymer increases absorption band peaks at 395 nm photocurrent quantum efficiency by (a = 129,000 cm-1) and has a FWHM a factor of five (see Figure 1). linewidth of 24 nm. Strongly coupled Quantum efficiencies of 15% have microcavities with PBPS as the been achieved and we are currently active layer show the expected anti- studying alternative polymers and crossing between the cavity photon device structures to enhance and exciton modes and a giant Rabi photocurrent generation. splitting of ² 430 meV between upper and lower polariton branches Fundamental research on the at resonance. LEDs have been mechanisms of charge transport in Figure 2. A polymer laser in action: made with this polymer and strongly organic hole transporters and the Photograph of a red emitting two-dimen- coupled structures are under investi- sional distributed feedback laser. This nature of contacts with metallic gation. Novel physical properties, work results from the Ultrafast Photonics electrodes is essential to understand Collaboration with St Andrews University including so-called Boser action the behaviour of organic solar cells (I. D. W. Samuel and G. A. Turnbull). (polariton lasing) may also be antici- 11 gating modes in amplifiers and lasers. In addition, the ordering that accom- panies orientation is very beneficial to charge carrier transport, with conse- quent benefits for the performance of FETs, LEDs and photovoltaic devices. Surface enhanced Raman Scattering (SERS) in single molecules P. G. Etchegoin and L. F. Cohen

Surface Enhanced Raman Scattering (SERS) has experienced breathtaking Figure 3. Microcavity structure fabricated for the observation of strong coupling progress towards single molecule between PBPS exciton states and cavity photon modes. The DBR mirror comprised detection and novel applications at nine pairs of l/4 layers of SiO2 and HfO2, with R = 99% at 390 nm. The PBPS layer was spin-coated to a layer thickness between 80 and 140 nm to control the normal the interface with the life sciences. incidence de-tuning between exciton and photon modes. The resonance condition is The study of biomolecules with SERS angle tuned since the exciton is so tightly bound (EB Å 500 meV) that temperature and is in itself not new. However, the depth electro-optic tuning are ineffectual. PBPS samples were provided by Professor Julian Koe. and breadth of the problems that pated and as such they are of both interactions) together with a well can be addressed with SERS at the fundamental and applied interest. defined sharp feature at the glass interface with biology have undergone transition temperature. We have been dramatic change, made possible by Glass transitions and molecular able to show that, in contrast to the instrumental breakthroughs. Novel orientation in thin polymer films situation for polystyrene, there are in applications in biology include cancer monitored by Raman Spectroscopy fact two glass transitions associated gene detection, spectroscopy of living H. M. Liem, J. Cabanillas-Gonzalez, with surface and bulk regions for cells, and single protein/DNA detection. K. S. Whitehead, P. G. Etchegoin conjugated polymer films. Under- Progress in non-biological applications and D. D. C. Bradley standing these characteristics is has been equally spectacular, starting important both for improved polymer from the pioneering demonstration of We have recently used Raman device stability and fundamental single molecule detection, to spectroscopy to study thermal phase knowledge of the differences between spectroscopy of single dyes in transitions in polymer thin films, saturated and conjugated polymers. nanocrystals, or SERS Stokes/anti- whose properties provide excellent Stokes spectroscopy in novel macro- examples of the competition between We have used polarized Raman molecules like carbon nanotubes. Our surface and bulk interactions. spectroscopy to probe molecular recent progress with single molecule Phase transitions are observed alignment in conjugated polymer thin SERS, includes: (i) applications to indirectly through their effect on the films either spin-coated or oriented ultrasensitive chemical analysis (~100 frequency, intensity, and width of the in their thermotropic mesophase. In attomolar sensitivity), (ii) single Raman active modes. An example is particular, we have demonstrated its molecule photobleaching, and (iii) shown in Figure 4 where the most superior performance over conven- dynamic SERS hot-spot phenomena. intense Raman active mode of tional dichroism measurements as a polystyrene displays a softening for probe of the degree of alignment in increasing temperatures (anharmonic thin films. Polarization ratios of up to 80:1 are measured indicating excellent orientation. The superior performance of Raman arises as a consequence of the close association of specific Raman mode tensor components with the molecular axis direction. This contrasts with the dipole-allowed optical transitions that have significant off axis components to their transition moments. The oriented film samples offer exciting Figure 4. Raman shift as a function of opportunities to fabricate polarized sample temperature for the phenyl ring stretching mode of polystyrene. Both emission devices that can be used parallel and perpendicular shifts reveal to backlight liquid crystal displays Figure 5. Detection of a single rhodamine a strong feature at the glass transition and through their large birefringence molecule in a 0.3 attomole solution after temperature (Å 76¡C). allow dielectric control over propa- 3 hours of SERS scanning. 12 An example is shown in Figure 5 heterojunction MOS and SiGeC where a single rhodamine molecule heterojunction bipolar devices. A has been detected in a 0.3 attomole novel growth method increases the solution after 3 hours of scanning. growth rate of Si/SiGe epitaxial films Attempts to transform this into a as well as enhancing the contrast standard technique for ultrasensitive between selective and non-selective chemical trace analysis are under way. growth over oxide masked substrates. Energy resolved channelling contrast Transport and Magnetism microscopy has been developed in collaboration with the National Measurement of Spin Polarisation in University of Singapore to investigate Highly Spin Polarised Ferromagnets the material properties of virtual using Andreev Reflection substrates. The unique depth and Techniques lateral spatial resolution capabilities Y. Miyoshi, Y. Bugoslavsky, of this technique provide 3D infor- R. A. Stradling and L. F. Cohen mation on lattice tilt. Initial investiga- tions showed that lattice tilts with Figure 6. The temperature dependence We are studying a range of highly similar spatial frequencies to that of (D(T)) of the two energy gaps as deter- spin polarised magnetic materials mined by point contact spectroscopy for the surface undulation exist with the aim of developing hybrid throughout the substrate. This infor- (a) film with Tc = 38K and (b) Tc = 30K. ferromagnetic-semiconductor devices. mation can be utilised to optimise The spin polarisation of a material can conducting gaps arising from different the growth conditions for the virtual be determined from the degree to parts of the Fermi surface. We have substrates. which the Andreev reflection from a been studying this rather fundamental superconducting tip is suppressed. aspect using tunnelling spectroscopy Carbon incorporation within the Experimentally conductance-voltage (see Figure 6) and high frequency base region of Si/SiGe hetero- curves between a superconducting techniques to look at how the density junction bipolar transistors [HBTs] is tip and a ferromagnetic metal are of states of quasiparticles and highly desirable. The growth of Cooper pairs evolve as a function of analysed as a function of temperature. Si1-yCy and Si1-x-yGexCy has been There are detailed theoretical descrip- temperature. studied by RHEED and TPD tions that allow for accurate modelling measurements under conventional of experimental data. The conductance We have made considerable progress GSMBE conditions. The growth rate curves can be well described if four understanding the limitations to the of the epitaxial films is reduced by parameters are included: a dimen- maximum current density Jc that the the presence of carbon. The sionless transmission parameter Z that super-conductor can sustain without dynamic changes in the growth rate dissipation in an applied magnetic describes the barrier transparency, a during formation of Si1-yCy quantum smearing parameter G that describes field. An on-going programme well structures also provide direct thermal smearing and sample inhomo- together with Dr Driscoll (Department evidence of surface segregation of geneity, the polarisation P (the degree of Materials at Cambridge University) carbon. The segregation process to which carriers are spin oriented in involves finding processing routes requires a substantial presence of a particular direction), and the super- that will generate similar disorder to carbon on the surface. The conducting gap D. The method has that created in the material by irradiation phenomenological model of surface been used to determine transport spin (collaboration with colleagues at segregation of Ge has been polarisation of Cu, Ni, and polycrys- Surrey). Underlying this work is an extended by direct incorporation of talline NiMnSb. understanding of how the critical growth process parameters into the magnetic fields Hc1 and Hc2 evolve as rate equations. This provided direct MgB2 - a new species of a function of disorder introduced into superconductor insight into the driving forces the material. The baseline study is to involved in the segregation process Y. Bugoslavsky, A. D. Caplin, examine the criticial field behaviour and produced excellent agreement L. F. Cohen, L. Cowey, Y. Miyoshi, in pure and irradiated single crystals. with experimentally observed

G. Perkins, M. Polichetti and Thin film epitaxy of Si/Si1-xGex/Si1-x-y surface and bulk concentration of A. A. Zhukov GexCy for microelectronics Ge. The model is currently being extended to the study of As and C After two years of intensive effort, it J. Zhang, G. Breton, A. N. Hartell, segregation. R. W. Price, E. S. Tok and N. J. Woods has emerged that MgB2 may be a fairly conventional superconductor, with the electron pairing mediated The gas source molecular beam by unusually strong coupling with the epitaxy [GSMBE] facility grows phonons. However, in one respect it structures to support two microelec- is unusual: There are two super- tronics projects involving SiGe/Si 13 Semiconductor Optoelectronics

R. Murray, G. Parry, C. C. Philips, and P. Stavrinou

The semiconductor optoelectronics section addresses a wide range of physical problems concerning the growth and development of new semiconductor materials (especially III-V systems) and their utilisation in a wide range of devices including Figure 7. (a) Resonant cavity and (b) Large fill factor PBG structures resonant cavity diodes, VCSELs, lattice, with holes of diameter ~ quantum wells, which are nanometer electro-optic modulators and solar 200 nm and depth ~0.5 µm. The wide regions of low band-gap cells. Interests include quantum dot size and separation of the holes semiconductor, absorb low energy semiconductors for data and telecomm determines the location and width of photons of light that would otherwise applications, single photon source the photonic bandgap. A "defect" pass through the host cell and thus devices for quantum cryptography can also be introduced in the PBG extend the absorption band-edge of and solid state quantum optics to create a resonant cavity, as high efficiency GaAs cells to longer (electromagnetically induced trans- shown in Figure 7(a). wavelengths to generate significant parency). Examples of recent current enhancement while preserving projects include: Incorporating active elements in good voltage performance. We have structures poses additional shown that the resulting carriers Photonic Crystal Technology for challenges, for example to achieve a escape from the well with high guided wave optoelectronics full band gap requires the overlap of efficiency. This leads to extra current S. Klengel, P. Caillaud, C. Palmer, the TE and TM polarisation band at a voltage above that achieved by P. Stavrinou, and G. Parry gaps. The width and spectral conventional cells made from the location of the bandgap is different well material, as long as the well Photonic bandgap (PBG) structures for TE and TM polarisation and very material has the same lattice constant are materials with periodic regions large fill factor patterns (large holes, as the host cell. of high and low refractive index. closely spaced as shown in Figure These 2D photonic crystals have a 7(b)) are needed to create a spectral The worldÕs highest efficiency cells band structure for allowed photon region where a full PBG exists. are monolithic, tandem cells formed of energies analogous to the electron Fabrication issues and tolerances GaInP and GaAs. The performance band structure in conventional become increasingly demanding, of this tandem is limited by the current semiconductors. Current interests in particularly as if in Figure 7(a), the produced by the lower band-gap these fascinating materials focus on PBG structure is to be combined GaAs cell. We have recently using the dispersion characteristics with existing guided wave technologies. demonstrated that were our SB- QWSC to replace the GaAs cell it of PBGs to control the propagation Novel Solar Cell Structures of very short (femtosecond) pulses would increase the worldÕs highest through a photonic circuit. This work K. W. J. Barnham, I. M. Ballard, efficiency tandem from 34% to 36% is part of the EPSRC funded Ultra- D. B. Bushnell, J. P. G. Connolly, at around 200 suns concentration. fast Photonics Collaboration (UPC) N. J. Ekins-Daukes, M. Mazzer and Our current primary research aim is led by St.Andrews University, a C. Rohr to optimise such tandem cells grown major collaborative programme by MOVPE at the EPSRC III-V involving 5 universities and 7 industrial Our group has pioneered the use of Facility at Sheffield in collaboration partners. Our efforts cover the nano-structures in novel strain- with a leading, European space cell theoretical modelling of PBGs and balanced, "Third Generation" quantum company. We intend to demon- the fabrication and optical assessment well solar cells (SB-QWSC). Such strate the cell in a concentrator of novel structures (fabrication is cells are expected to generate system, in collaboration with experts carried out in collaboration with John electricity at twice the efficiency and in UK and European universities and Heffernan at Sharp Laboratories of half the cost of "Second Generation" an UK concentrator manufacturer. Europe Ltd). Our approach involves thin film cells, and are already the combination of PBG patterns deployed on satellites. Before the We are also developing a novel, with existing waveguide technology. technology can enter the terrestrial non-tracking concentrator, which Single mode, 4.5 µm wide, rib solar cell market, costs must be uses the luminescence and quantum waveguides are typically used as a reduced with relatively cheap, light confinement properties of quantum base for the 2D Photonic circuit, concentrating systems. Our SB-QWSC dots. We have developed a thermo- while the PBG structures are cell offers significant advantages in dynamic model to optimise concen- generally patterned as a triangular high concentration systems. The trator performance, which demon- 14 strates that separation between and are progressing towards a LWI a separate "carrier" laser. Sideband luminescence and absorption can be demonstration. signals are just appearing, and, optimised by changing the spread of because of its promise as an efficient quantum dot sizes. We are researching The quantum cascade laser features all-optical wavelength converter for the properties of quantum dots, for an intense intra cavity radiation field, optical fibre telecommunications, the example their stability, high lumines- very strongly coupled to these same College has filed a patent on the cence efficiency and the possibility of ISB transitions, which have sharply device idea. tailoring their absorption edge, which peaked absorption spectra. This results, make them good candidates to uniquely, in a laser that operates replace the organic dyes of conven- between states that are "dressed" tional luminescence concentrators. by the laser radiation, allowing for the violation of the standard Einstein We are also applying our strain- population inversion arguments for balanced cell ideas to thermophoto- laser operation. In a new programme, voltaics (TPV). In this case low- we are studying this effect spectro- band-gap solar cells are used to scopically, using a resonant optical convert the radiant energy from frequency mixing scheme, to probe conventional power sources directly these "dressed" states inside the to electricity. We are collaborating laser diode via the resonant structure with Italian researchers to design an seen in THz sidebands produced on efficient and environmentally friendly, TPV system to extend the range of FiatÕs electric car. In collaboration with B.P Solar we are also studying epitaxially grown films of silicon to investigate the ultimate efficiency that can be achieved by thin film silicon cells. In addition, we have recently extended our funda- mental work on the determination of the quasi-Fermi level separation in quantum well systems to the light- biased situation. This work has important implications for questions on the ultimate efficiency enhancement possible with QW cells. Quantum Optics and opto-electronic devices in the mid-infrared J. Dynes, M. Frogley, A. Green, D. Gevaux , H. Zervos and C.C. Phillips

Quantum optics, i.e. the study of the optical properties of systems where not only the amplitudes but also the phases of the participating electronsÕ wave functions are under experimental control, is a rich branch of atomic spectroscopy. Effects such as lasing- without-inversion (LWI), ultra-slow light propagation and entanglement are attracting attention for their potential in quantum computation and communication schemes, but are rarely seen in solid-state materials. Figure 8. Electromagnetically-induced- transparency (EIT) in a quantum well. A laser Now, for the first time, we have seen tuned to E23 (128meV) establishes a phase relationship between matter-wave states these effects (Figure 8) associated |2ñ and |3ñ . Now, when the electrons ( in state |1ñ ) absorb light, destructive "matter- with "designer atom" intersubband wave interference" makes the sample transparent at a surprisingly sharp and (ISB) transitions in quantum wells, completely different (177meV) photon energy. 15 High Energy Physics http://www.imperial.ac.uk/research/hep

Head of Group: the highest energy machine in the Professor P. J. Dornan world, opening a new window of discoveries in particle physics. In Members of the Group exercise particular, it is expected that the significant influence in many of the elusive Higgs boson, which is the current and future international means by which the quarks and experiments that investigate the leptons in the Standard Model obtain fundamental particles and the forces their masses, will be identified. between them. A primary aim is to address basic questions such as the The CMS (Compact Muon Solenoid) origin of mass and the observed experiment, shown in Figure 1, is a asymmetry between matter and anti- general purpose detector being matter. Much of the programme is constructed at LHC. The Group has directed at discovering where the major roles in the detector design Standard Model, that has proved and construction, as well as the Figure 2. Top plot: the location of pion amazingly successful in the description scientific management of the project. beam particles in the RF cycle. Bottom: of electro-weak interactions, will break the fraction of events in each slot where down, since theoretical expectations The Group is active in the electro- a heavily ionising nuclear fragment was detected. The slow rise between imply that it cannot be the final story. magnetic calorimeter (ECAL) and the locations 0 and 12 demonstrates, and This will be accomplished by testing charged particle tracking system. predictions to high accuracy and allows to measure, deadtime in the In the ECAL electron and photon readout caused by very heavily ionising looking for phenomena outside the energies are measured by their nuclear fragments. model such as supersymmetry and interactions in lead tungstate crystals be used by the LHC machine. dark matter. read out by avalanche photodiodes Occasionally a nuclear recoil in the or vacuum phototriodes. In the last CMS silicon detector produces a very large year we have been making precise charge signal, equivalent to several T. Virdee, G. Hall, C. Foudas, measurements of the uniformity of hundred typical particles striking the D. Britton, W. Cameron, C. Seez, the light collection along the length sensor simultaneously, and much of M. Raymond, N. Marinelli, B. MacEvoy, of the crystals using a hybrid photo- the last year has been spent investi- G. Iles, E. Corrin, E. Noah, A. Nikitenko, multiplier device. It has been shown gating this effect and its consequences and X. Qu that the uniformity of most crystals is for CMS operation. Results from this sufficient and a technique has been study are shown in Figure 2. The Large Hadron Collider (LHC), is developed to improve the uniformity a new CERN accelerator under of those that fall outside the required Another Imperial-Rutherford Tracker construction due to begin operation limit. A new project is the design of a project now at an advanced stage is in 2007. It will collide protons at centre new amplifier for the electronic the development of off-detector of mass energy of 14 TeV and will be readout system. digital processing electronics (Front End Drivers) which digitize the The CMS tracker is a very large APV25 signals and reduce the data silicon detector system, which is an volume of 1-2 TByte/s by several area where we have two decades of orders of magnitude. expertise. Charged particles are measured by their bending in the 4T D0 at the Tevatron magnetic field using finely segmented R. Beuselinck, G. J. Davies, microstrip detectors read out with A. Goussiou, J. Hassard, J. Hays, low noise and radiation hard APV25 R. Jesik and P. Jonsson pipeline chips. The APV25 was developed by Imperial College The Tevatron, at Fermilab, near London and Rutherford Laboratory Chicago is the worldÕs highest energy and is based on commercial 0.25 µm particle accelerator, colliding together CMOS technology. protons and anti-protons at close to 2 TeV, putting it at the very forefront Recent work has concentrated on of discovery. It has recently resumed Figure 1. The Rector of Imperial College complete characterisation of the CMS running after extensive upgrades to Sir R. Sykes with Professors Dornan, readout system. Data were taken in both it, and the two general purpose Hall and Virdee during a visit at CERN a CERN pion beam with the same detectors around the ring, D0 and CDF. inspecting the CMS detector. 40 MHz radiofrequency structure to 16 Experiments to measure CP LHCb violation in High Energy Physics W. Cameron, P. Dornan, A. Duane, There is no evidence for significant U. Egede, D. Price, D. Websdale quantities of antimatter in the visible and R. White universe, yet any plausible theory of cosmology requires initially equal The LHCb experiment is an experiment amounts of matter and antimatter. for at LHC specifically designed to study CP-violation in the interactions of B-mesons to the ultimate precision. The elementary particles could provide aim is to provide measurements of Figure 3. B lifetime fit using inclusive the key to understanding this puzzle. CP-violation with the highest sensitivity and to look for new physics beyond B J/y decays BaBar the Standard Model. At a hadron collider the trigger (real- D. Bowerman, P. D. Dauncey, time selection of wanted events) is U. Egede, I. Eschrich, J. Martyniak, For the CP-violation studies particle critical due to the very large QCD G. Morton, J. A. Nash and D. J. Price identification is required to identify the background. The Imperial D0 group is flavour of the quarks participating in now the largest single group at Level-3 The BaBar detector is located at the the B-decay. Particles of a known (the highest level trigger), concentrating PEP-II electron-positron collider located momentum travelling through a medium in particular on tracking. Current activ- at SLAC in California. It is dedicated to with velocity greater than the speed ities include commissioning the overall the study of CP violation using B of light in the medium emit photons at a system, the development of track and mesons. BaBar made the first obser- fixed angle depending upon the mass vertex triggers and the development of vation of CP violation in B decays in of the particle. By imaging the emitted Ôb-taggingÕ algorithms, used to identify 2001 through the measurement of the photons onto a plane they will form jets containing b-quarks. Another parameter sin2b of the CKM matrix. rings where the radius identifies the critical area is the understanding of Using increased statistics, this measure- mass of the particle. In LHCb this is the energy scale of the jets of particles ment has since been improved to better done with two Ring Imaging Cherenkov produced after the proton anti-proton than 10% precision. Figure 4 shows the Detectors, RICH1 and RICH2. collision, and the optimisation of the current status of knowledge of the jet mass resolution. The D0 Jet Energy "Unitary Triangle" of the CKM matrix, To improve the projected perfor- Scale group is co-convened by an where b is one of the internal angles. mance of LHCb the experiment Imperial person and considerable design went through a substantial group effort is committed to this area. The Group is heavily involved in studies re-optimization of its tracking and of CP violation in charmless hadronic magnetic field configuration in 2002. Two of the main physics goals in the B decays. These decays are sensitive The implications for the RICH1 detector new run will be B-physics and the to a different CKM parameter, namely were large and the Group is respon- search for the Higgs boson Ð the sin2a, where a is another angle of sible for advancing the redesign from a elusive particle which is responsible the triangle. conceptual idea to a full design that for giving mass to all we see around satisfies demanding criteria. us. The Tevatron produces some trillion B mesons per year allowing ZEUS us to study CP violation, rare decays C. Foudas, A. Jamdagni, F. Metlica, and the ways b and anti-b quarks mix. K. Long and A. Tapper Results are already being produced (Figure 3 shows the B-lifetime as The HERA collider in Hamburg is a measured by Imperial College microscope used by the ZEUS personnel) and effort will focus now detector to look deep inside the proton. on B-mixing. A 27.5 GeV electron collides with one of the quarks inside a 920 GeV Activity is also already well underway proton, splitting the proton and throwing for the longer term goal of finding the out debris that can be detected. The Higgs. Within two years we will be proton structure is studied together able to answer whether LEP did see Figure 4. Status of knowledge of the with the nature of the strong force. the first hints for a Higgs at around parameters r and h which give the apex The Group has provided key pieces of 115 GeV, before extending the sensi- of the CKM Unitary Triangle, shown in ZEUS, which it helps run and maintain. tivity to ~180 GeV in the following black. The coloured bands show constraints years. from various measurements. The recent The Group has made leading contri- BaBar measurements of CP violation give butions to the analysis of neutral and values of sin2b, shown as the blue hashed areas, which significantly constrain the charged current events. We have available parameter space. measured the neutral and charged 17 current cross sections in both electron- matterÕ known to exist in the universe, electronics for a prototype high- proton and positron-proton scattering. but they give rise to the possibility of granularity electromagnetic calorimeter. The results are shown in Figure. 5 CP-violation in the lepton sector. The aim of the collaboration is to test where the cross section is plotted as a this prototype in a beam in 2004. function of the momentum-transfer in the There is a worldwide consensus that Technology Transfer Activities collision squared. We have also the tool of choice for the study of the taken an important role in the inves- properties of the neutrino is a Neutrino J. Hassard, J. Harford, C. Lee, tigation of both real- and virtual-photon Factory: an intense neutrino source P. Martin, M. Richards and D. Sideris structure as well as studying jet based on the decay of a stored muon production in deep inelastic e+p beam. The Group personnel have Our main focus has been in transferring scattering. played key roles in establishing the particle physics techniques, technologies physics case for a Neutrino Factory and approaches to high throughput From June 2003 HERA will run with and in defining the machine and discovery systems. We have devised a high intensity polarised electron and detector R&D programme for the UK. core platform technology capable of positron beams. We shall measure, The present focus of this programme using algorithms sufficiently precise to for the first time, the polarisation is the international Muon Ionisation gain back the factor of approximately dependence of the neutral and charged Cooling Experiment (MICE). MICE 107 signal lost by removing radioactive current cross sections and use the data seeks to demonstrate a novel labels, the Label Free Intrinsic Imaging to search for physics not described technique by which the phase-space (LFII) paradigm we pioneered. We by the SM. Crucial to this programme is occupied by a muon beam is reduced have successfully achieved the a precise measurement of the lepton by passing it through a lattice of capability of sequencing DNA up to beam polarisation. We have taken absorbers followed by accelerating RF- many hundreds of base pairs, with no the lead in the development of a cavities. We proposed the scintillating labels, at rates approximately 1000 position detector that will allow the fibre tracker that forms the baseline times that of the conventional technology. required precision to be obtained. instrumentation for the MICE We recently made the worldÕs first spectrometers. A crucial input to the separation of different glycoforms of MICE experiment is the precise protein in a real-time label-free system. measurement of the scattering Our LFII system has been adopted distributions of muons as they pass by a major pharmaceutical company. through matter. We have played a Our high throughput analysis systems leading role in the MuScat experiment won the Platinum (Top) Prize in the that will measure these distributions. IEEE ÔSupercomputing 2002Õ conference in Baltimore. Calice D. Bowerman, W. Cameron, Grid Computing Projects P. D. Dauncey, D. J. Price and O. Zorba D. I. Britton, D. J. Colling, P. Lewis, B. MacEvoy, J. A. Nash and R. Walker Over the last few years, a worldwide effort has started building towards a The current and future generation of Figure 5. The ZEUS measurement of high energy electron-positron linear High Energy Physics experiments will the neutral and charged current deep collider with a centre of mass energy produce massive amounts of data that inelastic scattering cross sections. The in the range 500-1000 GeV. Assuming will far outstrip the capability of existing fact that the four cross sections have the Higgs is discovered at the LHC, computing to store and process them. equal magnitude at high values of Q2 is the linear collider will allow precision In order to resolve the situation R&D a result of the unification of the weak measurements of any Higgs (or is taking place into greatly improving and the electromagnetic force. SUSY) particles in this mass range distributed computer processing Neutrino Experiments as well as having a significant employing "Grid" technologies. The E. McKigney, A. Jamdagni, K. Long, discovery potential of its own. Grid is an innovative system for P. J. Dornan and W. G. Jones connecting computers around the globe, The calorimetry for a detector at the allowing them to share the work of The neutrino has long been thought linear collider needs to be able to storing and processing information. to have no mass and to occur in three reconstruct jet energies with resolu- Work on prototype Grid projects is distinct flavours. This assumption has tions exceeding anything previously underway in many centres in Europe been built into the Standard Model. achieved if it is to fulfill the physics and the US; we have a team of people However, recent experiments have potential of the machine. The Calice investigating several aspects of Grid shown that neutrinos have mass and collaboration has been formed to study computing including Grid scheduling that neutrinos mix. The consequences both electromagnetic and hadronic and job control. In this work we of these observations are far reaching; calorimetry for a linear collider detector. collaborate closely with the not only do they imply that neutrinos The Group joined the collaboration Department of Computing and the form a significant part of the Ôdark in 2002 and is designing the readout London e-Science Centre. 18 Laser Consortium http://www.lsr.ph.imperial.ac.uk/consortium

Director: Strong Field Theory sufficiently high energy re-scattered Professor J. P. Marangos electrons the interference between P. L. Knight, M. Lein, J. Marangos, the two scattering centres leads to The Blackett Laboratory Laser L. Gaier, and K. Burnett. constructive and destructive inter- Consortium is carrying out research ference of the scattered wave as a that explores the new frontiers of A theoretical problem on which we function of scattering angle. In Figure science made possible by high power have recently been active is high 1 the angle dependent scattering of ultra-short laser pulses. This exciting order harmonic generation (HHG) electrons at an energy of 250 eV from area of science includes controlling + and more generally the dynamics of a H2 molecule are shown for two molecular and chemical processes, strongly driven electrons in molecular different inter-nuclear separations generating attosecond duration light systems. This has contributed to a (2.5 x 10-10m and 5x 10-10m). The pulses, producing coherent radiation better understanding of our earlier fringe spacing in the interference in the X-ray region and creating high experiments on high order harmonic pattern can be directly related to the energy density plasmas. We operate emission in molecules. Theoretical inter-nuclear distance in these two two high power lasers, a sub-picosecond + investigations of these effects in H2 cases. This is an example of electron glass system delivering over a joule and H2 molecules have enabled us diffraction, but in a unique regime per pulse, and a 50 fs titanium: to establish a picture for this process where the electrons are derived sapphire system delivering 100 mJ and to quantify the role of dipole internally from the molecule itself by pulses. Using these lasers and through phase and amplitude in random and the strong field. In principle this our accompanying theoretical work aligned ensembles of molecules. A could provide structural information we are making pioneering contribu- numerical integration of the Schršdinger on the molecule on a sub-Angstrom tions to the fields of ultra-short pulse equation was performed for the electron distance scale with sub-femtosecond generation, non-linear optics, plasma in a suitable two centre potential temporal resolution. physics, and molecular dynamics. exposed to a short intense laser We are funded by a £1.4M programme field. A quantum interference effect In collaboration with the NRC in grant from EPSRC/MOD and have in the electron wavefunction is seen Canada we are carrying out calcula- received substantial additional funding to suppress emission of certain tions of the modified multi-photon from both the EPSRC and the harmonic orders at a critical angle. ionisation that can occur in a European Union (COCOMO Research Essentially, contributions to the dielectric medium in a strong field. Training Network). We are engaged in harmonic emission from the driven This has implications for new a number of international collaborations electronic dipole are cancelled due techniques of creating microscopic with groups in Europe and North to the existence of contributions of optical structures by laser induced America. The Blackett Laboratory equal magnitude but opposite sign modifications of glasses. Laser Consortium forms part of the emitted by the two atomic centres of High Intensity Laser Development Quantum Optics and Laser Science the molecule. Group. K. Mendham, E. Sali, E. Heesel, The interference we have identified J. W .G. Tisch and J. P. Marangos A large programme on Attosecond is general in nature and should apply Technology Ð Light Sources, Metrology to all molecules. Moreover it also Work has been completed on the and Applications supported by the applies to the electron re-scattering installation of an all reflective, broad Basic Technology Programme of the from the molecule. Our most recent band, spatial light modulator (SLM) UK Research Councils has just been calculations have verified that for into our Ti:Sapphire femtosecond announced. We will be the centre of this £3.5M national programme, collaborating with Kings College London, Rutherford Appleton Laboratory, and the Universities of Oxford, Reading, Newcastle and Birmingham. The attosecond system will be located within our laboratories following the completion of the current SRIF funded building up-grade.

Figure 1. Angular distribution of scattered electrons 19 laser system. The SLM is a very powerful tool that allows us to create arbitrarily shaped laser pulses through control of the delay of individual frequency components of the laser beam. A diffraction grating and cylindrical mirror separate and collimate the different frequency components of the laser beam onto a liquid crystal phase mask made up of 640 pixels. The beam is then spectrally recombined using an identical cylindrical mirror and diffraction grating. Each pixel can be controlled individually and delays the light passing through it by an amount proportional to the applied voltage, allowing fine control over the shape of the laser pulse. Current work includes the devel- opment of a genetic algorithm to control the light modulator via feedback from an experiment that will generate pulse shapes that optimise a specific outcome of the Figure 2. Multiple-order Raman spectra excited by a pair of ~100 fs pulses. experiment. molecule. The OPG is driven by the (1014 W cm-2) pulse. We believe that second harmonic of the fundamental the enhancement arises from the A Frequency Resolved Optical and seeded by white light derived by better control in aligned molecular Gating (FROG) diagnostic based focusing a small portion of the ensembles of the phase of the non- upon polarization gating was also fundamental into a CaF crystal. An linear polarisation responsible for constructed and installed this year. energy per pulse of up to 1 mJ has harmonic emission. Further experi- This gives us the capability to fully been obtained in the resulting ments in the past year on a variety analyze the optical phase and tuneable output. We focus both the of molecules including CS2 and CO2 amplitude for laser pulses at around remaining fundamental and the output as well as various atoms have 800 nm with a pulse duration of the OPG (typically ~100 mJ in each) contributed to an improved under- between 3 ps and 30 fs. into a hollow core fibre containing standing of the complex interactions Non-linear Optics in Intense Laser the molecular sample at a density of that occur when molecules are Fields ~500 mbar. Both H2 and CH4 were exposed to intense laser fields. studied. Both showed greatly enhanced Cluster Heating Studies E. Heesel, E. Sali, K. Mendham, side-band generation if the pair of N. Hay, J. Robinson, J. W. G. Tisch, Raman resonant pulses were introduced K. Mendham, N. Hay, J. W. G. Tisch, R. de Nalda and J. P. Marangos compared to the case of a pump R. A. Smith and J. P. Marangos alone (see Figure 2). Work using A major activity in the last year has adiabatic techniques to drive high Our previous research has shown been to explore ways to produce sub- vibrational coherence is also reported that clusters of atoms comprising femtosecond intense laser pulses. elsewhere (see QOLS group section). more than about 1000 atoms can be One promising technique is based very efficiently heated with intense upon stimulated Raman scattering The anisotropy of molecules plays a (>1015 Wcm-2), femtosecond laser from strongly driven molecular vibra- significant role in HHG. We previously pulses. The heated clusters explode tions. We have employed two short highlighted the role of molecular to produce electrons with energies laser pulses tuned to Raman alignment upon HHG. We produced in the keV range and highly charged resonance to greatly increase the alignment in molecular samples ions extending out to 1 MeV. When efficiency of side-band generation (e.g. CS2) using the electric field of a laser-irradiated deuterium cluster compared to the case when a single a 300 ps duration laser pulse explodes, the kinetic energies of the frequency is applied. The laser derived from the stretched pulse of deuterons are even sufficient to drive fundamental at 800 nm and the tunable our Ti:sapphire laser. The alignment nuclear fusion, providing a short- output of an Optical Parametric technique allows us to modulate and pulse (ps) source of neutrons. Also, Generator (OPG) are tuned into enhance HHG produced by the the plasma that is formed when a Raman resonance with the main recompressed (70 fs), high intensity high density cluster medium is laser- vibrational modes of the chosen 20 the peak of the laser pulse, the ion energies are increased. Whether this is achieved with a pre or post-pulse depends on the atomic species, cluster size and main pulse duration. These results suggest that much bigger increases can be achieved using the aforementioned shaper to make more complex pulse shapes. Plasmas formed from Cluster and Microdroplet Media Figure 3. Pre-pulse timing dependence Figure 5. Ion yields as a function of of cluster heating. D. Symes, A. Moore, J. W. G. Tisch energy from laser irradiated micro- and R. A. Smith droplet targets fitted by numerical heated becomes a very bright hydrocode modelling. emitter of x-rays in the keV range, modulated blast-waves can be used producing very little debris. Owing to Microscopic objects such as atomic clusters containing a few thousand to investigate how expanding these applications, interest in this supernova interact with the cold field continues to grow. atoms are extremely fragile and easily destroyed by raising their temper- interstellar medium. ature several tens of Kelvin. Despite The recent focus of our research has The interaction of short, intense been to see whether the heating of this, they provide a unique and very effective way of producing high energy laser pulses with micron-diameter a cluster can be made even more liquid droplets has been further efficient by changing the shape of density plasmas in the laboratory. In an intense, sub-picosecond laser investigated by using ion the laser pulse, since it is known spectroscopy, supported by detailed that the dynamics of the interaction field clusters are ionised and expand on a timescale of a hundred numerical modelling. Ion yields from are sensitive to the time-dependent single droplets irradiated by 100 fs laser field the cluster "sees". We are femtoseconds. During this expansion they undergo a transient plasma laser pulses focussed to intensities of currently installing a pulse shaper 1016 and 1017 Wcm-2 are shown in into our high power Ti:sapphire laser resonance and large amounts of energy can be transferred to the Figure 5. The closeness of the target system that will allow us to control diameter to the laser wavelength the pulse phase and amplitude, cluster. Individual clusters then explode and produce an extended produces electric field hot-spots permitting us to synthesise almost across the droplet surface which any pulse shape. Ahead of this plasma with a mean temperature of several KeV. We have used the drive non-uniform heating. The development, we have been experi- droplet surface undergoes a highly menting with laser pulses that have fragility of atomic clusters, together with their ability to absorb intense anisotropic, polarisation dependent small (<10% of the main pulse explosion, generating energetic intensity) pre- or postpulses, which laser light to carry out a new series of experiments on modulated blast- multi-keV ions and causing a we can generate easily within the compression of warm core material. existing laser system as a stepping- waves. By destroying clusters in selected regions of an extended The subsequent core expansion stone to more sophisticated pulse does not depend on the laser polari- shaping. We were also able to change medium with a low power laser we can tailor the energy deposited by a sation, since the temperature the duration of the main pulse. We throughout the target has equili- found that the ion energies from high power pulse. Figure 4 shows a modulated blast wave produced in brated by this point in time. The exploding Xe, Kr and Ar clusters (of surprisingly non-spherical character about 5 nm in radius) differed by up this way, and imaged with a sub- picosecond optical probe. These of the droplet explosion found in to a factor of 2 depending on whether experiments can be explained by a prepulse or postpulse was used modelling the non-radial pressure (see Figure 3). Compared to a pulse gradients which deform the target without pre or postpulses, the increase during compression. The acceler- in ion energy is more than a factor ation of ions to high energies we of 2. have observed also indicates the future potential of microdroplets as a Detailed simulations of the laser- source for applications such as cluster interaction show that the proton radiography, isotope presence of a pre or postpulse production and short-pulse neutron changes the timing of a resonance generation. in the cluster heating that is known Figure 4. Electron density plot of a laser to be responsible for the high ion generated modulated shockwave in a energies observed. Essentially, when "machined" H2 cluster medium showing the resonance is shifted closer to a transition to "thin shelled" behaviour. 21 Photonics http://www.imperial.ac.uk/research/phot Head of Group: the deep UV. Professor P. M.W. French Although basic research on Raman The broad themes of our research are: amplifier configurations has ceased, adaptive optics applied to astronomy they have been extensively deployed and medical imaging; biomedical optics in simple pulse length-, wavelength- and photonics, including high-speed and repetition rate-tunable femtosecond/ Figure 1 (a) A single walled carbon 3-D imaging and fluorescence lifetime picosecond pulse sources exploiting nanotube (SWNT); (b) cross-section of imaging; electromagnetic theory, adiabatic amplification of optical SWNT; (c) multiwalled nanotube particularly of chiral media, Bragg solitons. We have also developed a (MWNT); (d) biological microtubule (MT) formed from tubulin dimers. structures and negative index media; new optical time domain reflectometry high power fibre laser technology, technique for measurement of gain laser efficiency and output beam including telecommunications ampli- in distributed and lumped Raman quality by exploiting a novel dynamic fiers and sources, nonlinear fibre optics amplifiers. We have also characterised holography process within the laser and compact high power visible/UV the Raman gain of "holey fibres" and amplifier itself. Building on our sources; optical fibre sensors, high found that devices based on earlier work using pulsed lamp and power solid-state laser technology conventional fibre typically offer laser pumped systems, we have and nonlinear optics; ultrafast diode- higher performance. demonstrated continuous-wave pumped solid-state and fibre laser diode-pumped solid-state laser with technology and optical storage. One area where "holey fibre" has a adaptive resonator operating at many tens of watts with diffraction-limited Optical Fibre Laser Technology unique characteristic is in the ability through modification of the waveguide beam quality. Currently we are S. Popov and J. R. Taylor to tailor the zero dispersion wavelengths developing adaptive interferometers to the visible wavelength range. for a range of real-world applications With the continuing downturn in the Consequently, anomalous dispersion including remote ultrasound detection optical telecommunications market, leading to soliton-like pulse shaping for non-destructive testing, medical the emphasis placed on the research is now possible in the visible range biomechanical health and free- programmes undertaken throughout in all-fibre format. We have demon- space optical communications. A 2002 has reflected our belief that strated thus the first all-fibre programme to characterise new optical fibre based devices will play femtosecond Yb doped "figure of nonlinear optical media complements major roles in important fields outside eight" laser. Various other novel the work on nonlinear optics. As telecommunications. As a consequence, configurations for all fibre femtosecond well as including the conventional bulk our research on basic broad-band generation in the visible and near nonlinear crystal media such as amplifiers, specifically that on fibre infra red are currently under investi- KTP, we have work extensively with Raman devices, has been drastically gation. Holey fibre has also allowed photorefractive media that have reduced. up to 5W, high power broad-band strong nonlinear effects even at low continua to be produced pumped by light levels ~ 1 mW. Our development of MOPFA (Master MOPFA configurations in all-fibre Oscillator Power Fibre Amplifier) formats. We are developing novel high power technology has continues to focus solid-state laser devices for a range on versatile compact seed sources Nonlinear Optics and Laser of applications ranging from indus- that are deployed with high power, Technology trial processing to medicine, laser fibre-based amplifiers (Yb, Yb-Er and M. J. Damzen displays and information technology. Raman) to generate high average Our novel side-pumped designs power sources with versatile wavelength A key problem to scaling the power operate at high output power levels and pulse format. These sources are of solid-state lasers are strong (10-100 W) with record conversion particularly applicable to non-linear heating effects in the laser amplifier efficiencies (60%-70%) for bulk optical conversion allowing extended leading to thermally-induced lensing solid-state lasers. These sources wavelength coverage. A particular and stress-induced birefringence that are expected to have immediate highlight of the year has been the degrade beam quality and reduce impact for industrial material demonstration of multi-watt level, stability and efficiency of the laser. processing applications. By using compact, red-green-blue sources We have developed a range of different laser media and different based upon frequency doubling and nonlinear techniques to provide self- transitions with nonlinear frequency mixing of Yb and Yb:Er based organised correction of many of conversion, we our developing new MOPFA systems in periodically poled these adverse effects, pioneering compact efficient sources at high non-linear materials and extension of radically new self-adaptive solid- average power (multi-watt) in the the converted wavelength ranges to state laser systems that maintain the red, green, blue and UV spectral

22 regions for application including Electromagnetic Focusing and models to reliably predict imaging medicine and laser displays. Imaging and Applications to Optical properties of optical systems and it Data Storage permits the description of partially We are currently initiating a new coherent high aperture systems. nanotechnology programme to study P. Tšršk Our models also include polarisation nonlinear optical properties of effects and we are developing a carbon nanotubes and biological Current optical disc systems including method to produce an arbitrary microtubules for new materials for audio and data CD-systems and polarisation structure in the vicinity information processing and sensors DVD-systems (video and data) still of focus of high NA lenses. We take Figure 1. use the basic optical disc technology a combination of vectorial Gauss- developed in the seventies for the Laguerre and Gauss-Hermite beams Sculptured Thin Films storage of video signals. More recent as basis functions that we use to M. W. McCall developments explore the limits of expand a Ôwish functionÕ describing this classical approach and hence the polarisation structure in question. Sculptured Thin Films are formed by the wavelength of illumination has This research has great use in vacuum deposition of vaporised been shortened and the numerical optical data storage, ellipsometry material onto a substrate that moves aperture (NA) increased. In its most and polarised light optical microscopy. in a periodic fashion during growth. advanced version, the optical disc For a rotating substrate a chiral has to be in quasi-contact with the High Resolution Imaging of the morphology results in which the upper surface of an ÔimmersionÕ lens, Human Retina using Adaptive Optics material forms into helicoidal columns leading to an effect size of approxi- D. P. Catlin, J. C. Dainty, I. Munro, (Figure 2). Chiral sculptured thin mately one third of the wavelength C. Patterson and F. C. Reavell which is therefore the limiting feature for information density increase. The The human eye has significant vulnerable aspect of this immersion optical defects that distorts an optical option is the quasi-contact between wavefront passing through it blurring the last lens surface and the optical the retinal image. In order to obtain disc. Our research aims at overcoming high resolution retinal images that this problem and increasing the data allow individual photoreceptors, density as shown in Figure 4 indicated approximately 2 mm in diameter, to by SLAM. be observed requires the wavefront aberrations of the eye to be accurately We are researching various means measured and corrected for across Figure 2. Scanning electron micrograph to achieve this aim, including super- a wide, dilated pupil. The wavefront of a chiral sculptured thin film (courtesy resolution techniques by means of aberrations of the human eye are of Pennsylvania State University). transfer function equalisation, super- recorded by using a Shack-Hartmann films have some promise for various resolving filters and multilevel coding. wavefront sensor, which consists of sensing and filtering operations, as Our ultimate goal is to exploit the a compact tightly grouped array of their properties are selective to maximum information content by lenslets. The device is located in the circularly polarised light. Our recent unit area that is possible to store on light path in such a way that each research has shown how chiral mirrors an optical disk. tiny lenslet forms an image of the can be used to design a circularly retina on the surface of a CCD. If polarised resonator (see Figure 3). This optical data storage work makes the light wave is perfectly flat then use of our research developing each lenslet produces an image spot numerical methods, such as Finite located at the focal point of each Element (FE) and Finite Difference lenslet. However if the light wave is Time Domain (FDTD) for analytical not perfectly flat then the images models of optical systems including produced by the lenslet array are the notoriously difficult high aperture shifted from their central positions. optical systems. Fully analytical Measuring the displacement of each models may only be constructed spot provides a snapshot of the light when the specimen is much smaller beamÕs aberration. Once the slope than the wavelength or it has special measurements are known the properties, such as full rotational wavefront aberration is reconstructed symmetry. The interaction of tightly using a series of Zernike polynomials. focused light with complicated Imaging is achieved by using a Figure 3. (Upper) Open cavity handed resonator formed using a pair of chiral specimen structures must be Fourier deconvolution technique. mirrors. (Lower) Spacerless handed computed by means of numerical The method uses multiple wavefront resonator. methods. Our research aims at aberration data and multiple degraded incorporating analytical and numerical images to provide an ensemble

23 acquisition, offering sub-10 ps temporal discrimination for wide-field functional imaging of chemical and biological samples, contrasting different chemical species and different fluorophore environments.

We have worked to combine FLIM with multi-spectral imaging and optical sectioning to realize 5D fluorescence imaging and have adapted FLIM to polarization anisotropy to image rotational diffusion dynamics. Our novel FLIM instrumentation is complemented by a confocal scanning/multiphoton microscope Figure 4. The development of data densities on several types of storage media and broadly tunable ultrafast laser throughout the years, and the expectations for the future. An expected huge jump technology to provide a unique can be made using new technologies like SLAM opportunity for functional biomedical imaging. This resource is being maximum likelihood estimate of the use of photorefractive GaAs/AlGaAs developed for collaborative projects undistorted object. In this way we MQW devices, in partnership with with the Bioengineering, Biology, aim to produce high quality in vivo David Nolte at Purdue University, Chemistry Departments and the images of the human retina that will has realized wide-field depth resolved Faculty of Medicine. In molecular provide new opportunities for imaging at ~ 500 frames/second. biology FLIM is used with genetically studying vision and for clinical expressed probes such as EGFP, to diagnosis. We have also investigated other report not only the localization of the techniques for wide-field optical Functional imaging for biology and specific protein to which the EGFP is sectioning including low coherence medicine tagged, but also the local fluorophore interferometric imaging with direct (protein) environment. For medical P. M. W. French, I. Munro, M. Neil CCD detection and structured illumi- applications FLIM provides intrinsic and F. C. Reavell nation. Potential biomedical appli- contrast from autofluorescence of cations include a safe, low-cost, unstained tissue samples, as shown Throughout 2002, we have continued non-invasive optical biopsy tool to in Figure 5, with potential applications to develop ultrafast laser based study and screen for skin cancer and to non-invasive diagnosis of disease technology for novel imaging appli- other diseases. These techniques and to in situ quantitative monitoring cations with a strong emphasis on are also generally applicable for 3-D of tissue during therapeutic inter- biomedical imaging and microscopy. microscopy of dynamic (living) subjects vention. We have recently received Our philosophy is to develop new and on a macroscopic scale may be a DTI Beacon Award and a Wellcome imaging technology for both clinical used to image large (including remote) Trust Showcase Award to develop and interdisciplinary research appli- 3-D objects, e.g. for facsimile trans- FLIM and related technologies for cations that can exploit state-of-the- mission or input into 3-D graphics biological research, clinical evaluation art and future anticipated ultrafast software. Our fluorescence lifetime and high-throughput assay technology. and tunable laser technology imaging (FLIM) programme also including compact diode-pumped all- concentrates on wide-field image solid-state and fibre laser sources.

Currently we are focusing on two main areas: 3-D imaging using coherence gated imaging and fluorescence lifetime imaging (FLIM). The former programme builds on our invention and development of time-gated imaging using low coherence photorefractive holography to provide a unique 2-D and depth- resolved 3-D imaging modality, Figure 5. FLIM of biological tissue: applicable through scattering media, intensity modulated fluorescence lifetime that offers an inherent rejection of a map of a section of human bone and dc (diffuse light) background. The cartilage

24 Plasma Physics http://www.imperial.ac.uk/research/plasma

Head of Group: Fusion plasmas confined by magnetic fields generated at or near the critical Professor S. C. Cowley fields are plagued by turbulence and surface. However, we have made instabilities. We have developed measurements of the self generated The Plasma Physics group studies computational techniques and codes magnetic field during an ultra-high ionized gases and their interaction to simulate the turbulence. Recently intensity (>1019 Wcm-2 ) short pulse with electromagnetic fields in the quiescent states that greatly enhance (0.7 - 1 ps) laser-plasma interaction laboratory and the universe. A large the fusion performance have been experiment using an innovative method. part of the GroupÕs effort is directed discovered in experiments on JET. We have shown that polarisation towards the physics of schemes for Our simulations have shown how these measurements of self-generated generating fusion power. We perform states are created by turbulence driven harmonics of the laser can provide a theoretical, experimental and computa- sheared plasma flows. They have also convenient method for diagnosing the tional research in all areas of fusion shown that specific magnetic field magnetic field in these interactions - research. High powered lasers and configurations enhance the generation and that our experimental measure- pulsed power devices (such as MAGPIE of these turbulence free states. ments indicate the existence of fields in the basement of the department) Further work in this area to understand in excess of 340 MegaGauss. have produced novel high energy these states and how to access them These observations are important density states of matter that we are in ITER and other future devices is for evaluating the use of intense exploring. For example, using lasers we under way. lasers in various potential applica- have studied gigantic magnetic fields tions and perhaps for understanding (340 Mega-gauss) and relativistic One of the issues facing all magnetic the complex physics of exotic astro- plasmas. With MAGPIE we have made fusion concepts is the explosive loss physical objects such as neutron stars. jets that scale appropriately to astro- of plasma and the damage it causes Fast Ignition Experiments physical jets. Theoretical studies of astro- to the devices. We are measuring this physical plasmas focus on the origin of loss and the impact on the walls of K. Krushelnick, A. E. Dangor, magnetic fields and cosmic rays. the device. A new theoretical model F. N. Beg, M. Tatarakis, E. L. Clark, has been developed to explain the and I. Watts Magnetic Fusion Research explosive loss of plasma. In Figure1 we show the theoretically predicted One way of reducing the criteria for J. W. Ahn, D. Applegate, M. Coppins, finger of plasma that explodes to the ignition in Inertial Confinement Fusion S. Cowley, W. Dorland, N. Joiner, wall. The model predicts that the experiments is the so-called "fast P. Jones, F. Lott, J. Martin, A. Meakins, explosive loss may be made tolerable ignition concept" Ð in which the inter- J. Paley, and G.Turri. by shaping the plasma into a triangular action of an ultra-intense laser pulse In collaboration with Culham laboratory shape. with a dense plasma generates a high and at the Joint European Torus (JET) current electron beam capable of Ultra-high magnetic field heating and igniting a compressed the Group is investigating the physics measurements of magnetic fusion. This field is fusion pellet. One of the difficulties with preparing to build an internationally K. Krushelnick. A. E. Dangor, this scheme is the propagation of a funded experiment (ITER) that will, for M. Tatarakis, A. Gopal, F. N. Beg high intensity laser pulse through the the first time, ignite a plasma with and M. S. Wei long distance of low density plasma fusion reactions. Although we are which usually surrounds the deeply involved in the central issues Very large magnetic fields (up to 1 compressed core. However, we have this device will face, primarily turbu- GigaGauss) have been predicted by been working on a way of avoiding lence and explosive instability, we are computer simulations and analytical this problem through the use of conical also investigating various concepts calculations to exist in the high density implosions Ð which provides a clear to improve fusion plasma efficiency. region of the plasmas produced path for the high intensity pulse (see during high intensity laser-matter Figure 2). At the Institute of Laser interactions. In the past, the principal Engineering at Osaka University in diagnostic for magnetic field measure- Japan we have been involved in ments in laser produced plasmas has experiments in which all of the been Faraday rotation of transversely components for the Fast Ignition propagating external probe beams. scheme have been tested simultane- However, because of refraction effects ously for the first time. In these experi- only magnetic fields in the outer coronal ments, we have found that, by using plasma can be observed using this this conical compression geometry, a Figure 1. Explosive finger of plasma technique. These fields are up to 5 compressed pellet can be heated carrying a magnetic field line out of a MGauss, which is far lower than the significantly by the hot electrons fusion plasma from theoretical model. strength of the predicted magnetic created by the intense laser beam. 25 Wire array Z-pinch implosions plasma. This limits the ability of the driving current to follow the implosion S. V. Lebedev, J. P. Chittenden, down to the axis, which in turn S. N. Bland, D. J. Ampleford, controls the kinetic and Ohmic heat C. A. Jennings, M. Sherlock, and sources in the imploded plasma and M. G. Haines hence the X-ray power emitted. Laser produced plasmas as a One approach to achieving controlled compact particle accelerator thermonuclear fusion in the laboratory is to use X-rays from an imploding Z. Najmudin, K. Krushelnick, Z-pinch plasma to energise an X-ray A. E. Dangor, M. Tatarakis, E. L. Clark, cavity surrounding a capsule of B. Walton, S. Mangles, M.S. Wei, deuterium and tritium. Achieving A. Gopal, C. D. Murphy and external control over the shape of the M. G. Haines. X-ray power pulse is an important requirement for future Z-pinch driven High intensity laser produced plasmas fusion ignition experiments. We are are capable of accelerating particles currently exploring the use of two to high energies over very short concentric (or nested) arrays of fine distances. We have been exploring metallic wires for pulse shaping on our these interactions for this application 1.5 MA MAGPIE pulsed power facility. as well as examining the fundamental The shape of the TW x-ray pulse is physics of the propagation of ultra- controlled by the dynamics of the high intensity laser pulses through "snowplough" phase of the outer gaseous density plasmas. Figure 2. Upper figure: gold conical array implosion, and by the delay insert and deuterated plastic shell between the stagnation of the outer Recently we have measured plasma before implosion. and the inner arrays (Figure 3). electrons accelerated to energies in Lower figure: image of x-ray emission excess of 200 MeV in a distance of from implosion showing that compression only 1 mm. This electron energy is relatively uniform. spectrum was obtained using the high intensity laser at the LOA facility near Generating an axial magnetic field from Paris, which can be focused to photon spin intensities greater than 1019 W/cm2 in a 30 fs pulse. Particle-in-cell simula- M. G. Haines tions performed on our home-built computer clusters, as well as in 3D Photons have spin h and in circularly on supercomputers, have shown polarised light these spins are aligned, that the electrons are generated in a and lead to angular momentum in complex interaction of non-linear the beam. When a circularly polarised processes. This interaction severely laser beam is absorbed by a plasma, modifies the laser pulse (creating a the angular momentum is deposited sharp rising edge), which generates in the electrons at first, exerting a the required accelerating structure. torque which drives an azimuthal This mechanism has been called a current. For a pulsed laser an forced laser wakefield. azimuthal electric field is induced to oppose the torque on the electrons. It then follows from Faraday's Law that an axial magnetic field will be Figure 3. Implosion trajectories and X- generated. Estimates for the magnitude ray pulses from the single and nested of this axial magnetic field for photon wire array z-pinches. spin are in reasonable agreement Using our 3D resistive magneto- with the 7 MG fields recently deter- hydrodynamics simulation, we have mined experimentally by the Group. been studying the generation of X-rays during implosion phase of wire array Z-pinches. Non-uniform ablation of the wires results in a strong modulation 19 Figure 4. Electron spectra ne = 2.5´10 of the plasma flow injected into the -3 19 -3 cm (squares) and for ne = 6´10 cm interior of the array and later on (circles), showing extension of the spectrum causes a break-up of the imploding to > 200 MeV at the lower density. 26 The experiments are presently being scaled up to the recently commissioned Petawatt laser at the Rutherford- Appleton Laboratory, which can be focused to intensities in excess of 1020 W/cm2. Laser-plasma transport modelling R. J. Kingham, A.R. Bell, A. Robinson and M.G. Haines

Recent experiments involving the interaction of a ultra-high intensity, sub-picosecond laser pulse with thin solid targets have demonstrated the generation of beams of electrons and Figure 5. Schematic of transport and magnetic field generation in laser-solid interactions. ions with relativistic energies plus Laboratory experiments to simulate present state by turbulent motions of intense magnetic fields of 100's of astrophysical jets the constituent plasmas. There are MG (see Figure 5.) There are still two kinds of fields: small-scale fluctua- many open questions including how S. V. Lebedev, J. P. Chittenden, tions and large-scale structured the beams form and propagate A Ciardi, D. J. Ampleford, S. N. Bland, fields. through the target. M. Sherlock, and M. G. Haines Massively parallel supercomputers We have developed a new kinetic code, The emerging field of laboratory are being used to simulate the KALOS, that can model the transport astrophysics allows the non-linear turbulent dynamo - the process of of relativistic beams of electrons evolution of dynamical astrophysical magnetic-energy amplification from through a dense, cold, background plasmas to be studied in a series of tiny seed fields to dynamically plasma and the associated production directly scaled laboratory experiments. important levels - and the ensuing of strong magnetic fields in 2-D. One example is the use of the conical nonlinear self-consistent turbulent KALOS solves the Fokker-Planck wire arrays on MAGPIE, which result states. Using modern particle codes, equation and Maxwell's equations to in the formation of radiatively cooled we are also studying the large-scale correctly describe the WHOLE range plasma jets, that reproduce the dynamics of astrophysical discs and of electron collisionality. KALOS has behaviour of proto-stellar jets on the the emergence of structured been used to understand how the 0.1 parsec scale. The interaction of magnetic fields. laser energised electrons resistively the jet with target plasmas formed collimate into beams (due to self from X-ray irradiation of plastic foils generated magnetic fields) as they provides a scaled study of the propa- propagate through the target. In turns gation of proto-stellar jets through the out that beam formation is effective inter-stellar medium (Figure 6). even if the fast electron source is not strongly anisotropic and that the time- scale for beam formation is 0.5-1 ps for current experimental conditions.

We have also continued to address thermal transport and magnetic field generation in the plasma ablated Figure 6. Soft x-ray image of the from the solid (see Figure 5). laboratory jet interacting with plasma cloud.

Turbulent magnetic fields in Figure 7. Small-scale field structures in a simulation of MHD turbulence: astrophysical plasmas magnetic-field strength in a cross- section of the simulation box. S. C. Cowley, G. G. Howes, and A. A. Schekochihin

Astrophysical objects such as stars, accretion discs, galaxies and galaxy clusters all possess magnetic fields. These fields are believed to be generated and maintained in their

27 Quantum Optics and Laser Science http://www.imperial.ac.uk/research/qols

Head of Group: the temperature of molecular ions is quantum computer. Underlying this is a Professor G.H.C. New reduced through long-range Coulomb long-term research programme collisions with laser-cooled atomic ions concerned with the foundations of Research in the QOLS Group encom- held in the same trap. This might quantum theory, the nature of entan- passes a wide range of theoretical and produce a new way of preparing a glement, non-locality, algorithmic experimental projects in quantum optics, sample of ultra-cold molecular ions. complexity and the dynamics of quantum information processing, laser open systems. physics, and nonlinear optics. Our An exciting new area of experimental work on high-intensity light-matter quantum optics relates to quantum We have been very active in studying interactions is described in the Laser information processing, the ultimate potential realisations of quantum Consortium entry (pages 19-21). goal being the realisation of a quantum gates. Candidates include laser- Highlights of 2002 were the arrival computer. Our particular aim is to cooled trapped ions, atoms trapped of the cold atom physics group of study decoherence processes. We in optical lattices, cavity quantum Professor Ed Hinds and Dr Ben Sauer have recently achieved the first laser electrodynamics, guided atoms on from the University of Sussex, and the cooling of Ca ions in a Penning trap, "atomic chips", and solid-state return of Dr John Tisch to a Lectureship. and we are currently working towards excitations. To do so we use different cooling a single calcium ion. We have mechanisms to control a system IonTraps and Laser Cooling developed an improved technique for inside a non-trivial decoherence -free R. C. Thompson D. M. Segal and laser cooling in the Penning trap, in subspace. Other applications that S. de Echaniz which an additional external driving require good control over the time voltage is applied to the electrodes. evolution of open quantum systems Ion traps make possible many new are reliable single photon sources types of experiment in fundamental We take part in an EU research relevant to quantum cryptography. physics and quantum optics. Our network (HITRAP) concerned with the work falls into three categories: the study of highly charged ions in traps. Alternatively, geometric and topological dynamics of ions in traps; the use of We are developing novel spectro- time evolutions can be used for the laser-cooled trapped ions as a tool scopic techniques for probing the implementation of quantum computation in quantum optics experiments; and nuclear and atomic properties of these with a great robustness against errors. the study of highly-charged atomic ions. We have a collaboration with It has recently been realised that ions in the Penning trap. the Wavelength Standards group at elementary gates in quantum compu- NPL, where the modified spontaneous tation can be implemented using only emission of a single ion, mediated geometrical (as opposed to dynamical) by the presence of a high-Q optical phases. This approach has certain cavity is being studied. inbuilt fault tolerant features, such as resistance to some errors arising Quantum Optics and Quantum from the random interaction of the Computation quantum computer with its environment. P. L. Knight FRS, M. B. Plenio, One of the more promising physical V. Vedral, V. Kendon, K. Audenaert, realisations would be in quantum dots. J. Eisert, E. Kashefi, M. Lein, J. Pachos, M. F. Santos, S. Scheel, S. Virmani, Imagine that you flip a coin and look P. T. Greenland (UCL) and W. Munro to see if you get a head or tail; the (HP Labs) outcome is probabilistic. This basic Figure 1. Image of a single magnesium ion obtained using the "axialisation" element of classical randomness has technique developed in our laboratory. The Quantum Optics and Quantum a fascinating quantum counterpart. Information theory group is one of A quantum coin can, of course, be in Ion traps consist of electrodes that the largest of its kind in the world. a superposition of heads and tails, generate EM fields to trap ions for Our work centres on understanding and if it is used to determine the path long periods of time. Our experiments how quantum coherence can be of a quantum particle in a random generally start with the application of created, manipulated and exploited in walk on a lattice, the particle is in a laser cooling to reduce the ion dissipative environments that tend to superposition of locations. With a temperature to <1K. The ions are then destroy quantum resources through de- suitable definition of average proba- still not truly at rest, but oscillate at coherence processes. If we can bility distribution for this "smeared out" characteristic frequencies, which we understand how to manipulate quantum quantum particle, it turns out that the measure from the arrival times of coherence, we will be able to construct distance it walks grows linearly with detected photons. We are also inter- addressable quantum registers, an time (or number of tosses) rather than ested in sympathetic cooling, in which essential building block of any future the classical dependence on the 28 account the fact that the environment existence of correlated pairs produced interacts in an uncontrollable way with in a down-conversion process within the the system and apparatus, and reduces condensate can be identified by the efficiency of the measurement. It measuring the competition between turns out that this situation is more one- and two-particle transitions complicated than in EverettÕs analysis and that both the entanglement and We continued to study the properties of classical correlations then become unstable resonator modes with relevant. We have been investigating this emphasis on fractal properties. We kind of imperfect measurement and the undertook an in-depth study of the Figure 2. Comparison of the classical development of correlations and entan- Virtual Source method for generating (dotted) and quantum (solid) probabilities glement between various subsystems one-dimensional modes, and applied of displacement x for walks on a line: involved in the measurement process. the power method with translation to note the dominant quantum interferences extend the Fox-Li method to the square root of time (see Figure 2). This Quantum communication schemes two-dimensional case. feature relates to the speed up of that employ the superposition principle quantum computation over classical in and quantum entanglement are major We developed sophisticated computer the algorithms of Grover and Shor for applications in quantum information codes for modelling optical parametric searching and factorisation respectively. science. Indeed, a polarisation based processes both in optical parametric Two algorithms using quantum walks cryptography scheme has already chirped-pulse amplification (OPCPA) have been found recently, and we aim been demonstrated experimentally and in optical parametric oscillators to discover more. We have been over distances of many kilometres. (OPOs). We worked with Drs Ian Ross analysing GroverÕs algorithm under However, the manipulation of polari- and Pavel Matousek at RAL on the the assumption that quantum particles sation degrees of freedom is difficult detailed design of a three-stage are actually indistinguishable and obey when one aims at collective operations OPCPA prototype experiment that will either fermionic or bosonic statistics. between photons (e.g. as required for hopefully form the basis of a future This means that their total state has to quantum repeaters). We have been major upgrade of the Vulcan laser. be either symmetric or anti-symmetric. exploring a different route in which the In the OPO work, we collaborated We are investigating if this symmetri- continuous degrees of freedom of the with Professor Wilson Sibbett and sation postulate has any effect on light field modes are used rather than Dr Pablo Loza-Alvarez at St Andrews the quantum speed-up in general. the polarization degrees of freedom. in the successful interpretation of This promising approach offers a OPO tuning characteristics. Entanglements are extra correlations number of advantages concerning between quantum systems over and their experimental feasibility compared We developed our understanding of above those allowed by classical to other quantum systems. We are femtosecond nonlinear optics beyond physics. Although the process is well studying systematically the capabilities the slowly-varying envelope approxi- understood for two quantum systems, of such an approach with present mation and identified techniques for we still have very little understanding of technology. handling the situation where the spectra entanglement for a large collection of of different component fields overlap. systems. This is important because a Novel Laser Phenomena and We started to exploit the Finite- quantum computer will involve a large Nonlinear Atom and Photon Optics Difference Time Domain approach in number of qubits, and will therefore G.H.C. New, P. Kinsler, E. Grace, this context, and this is likely to be a involve manipulating large entangled T. AlBaho, J. Rogel, M. Yates and key focus of future work. We also made states. It is important to understand C. Tsangaris encouraging progress in the study of how the amount of entanglement is transverse effects in three-wave related to the potential speed-up in a Numerous theoretical projects in laser nonlinear interactions, especially in quantum computer. physics, nonlinear optics, and atom periodically-poled media. optics are in progress. Atomic Coherence and Quantum We have been investigating the notion Interference of quantum measurement and how to With Professor Keith Burnett (Oxford), understand and describe it fully quantum we have used the Q-function in a J. P. Marangos, M. Anscombe, R. de mechanically. The first description of phase-space representation to show Nalda, S. Gundry and D. M. Segal a fully quantum measurement (meaning that the ground state of a Bose- that both the system measured and the Einstein condensate in the Hartree We are using laser fields to create apparatus are quantum systems) was approximation is squeezed, due to coherent superpositions of quantum due to von Neumann in 1930. Everett interactions between the atoms. states of atoms and molecules, which later proposed an information-theoretic Multimode Schršdinger cat states are enable remarkable changes to be made understanding of the process without generated as the condensate evolves to the optical and nonlinear optical the use of the projection postulate. in a ballistic expansion. We have properties of an ensemble of molecules However, Everett did not take into proposed a technique by which the or atoms. During 2002 our experimental 29 research programme was focused on a dephasing upon the conversion The combination of cluster beams new project that employs excitation of efficiency in a four-wave mixing scheme. with pulsed lasers opens up the subject vibrational coherence in molecular of multiphoton excitation of metallic deuterium (D2) to create a medium clusters, whose spectra are dominated with unique nonlinear optical properties. by plasmon resonances. While the We use a pair of single mode pulsed study of plasmons in single-photon lasers (an injection seeded Nd:YAG and in collision experiments has been and a single mode tunable OPO) tuned a notable feature of cluster physics, close to a Raman resonance to most of the strong laser field experi- adiabatically excite a near maximal ments (including those at Imperial coherence between the v=0 and v=1 College London) have involved the vibrational states in the molecule fragmentation or explosion of clusters. (energy separation 2995 cm-1). This What we consider here is few-photon medium will then be used to modulate excitation of plasmons without a high power 50 fs laser pulse (from destruction of the cluster. We have the Laser Consortium CPA Ti:sapphire shown that two- three- and multi-photon laser), producing multiple sidebands excitations of plasmons in metallic by stimulated Raman scattering. clusters provide new information on Because this will be highly efficient their collective properties. Within current and all the molecules in the sample models, this type of information can will be equally phased in their vibra- Figure 3. The calculated evolution of be obtained theoretically, leading, it tional motion, a broad spectrum of populations and coherences in the is hoped, to new experiments. This phased Raman sidebands will be presence of photoionisation. work is performed in collaboration with produced that can in principle be used the Ioffe Institute in St Petersburg. to synthesise a sub-femtosecond pulse. Atoms in Crossed Electric and Work on providing the two laser fields Magnetic Fields, Atomic Cluster Our work on confined atoms has been at the correct frequencies and with Quantum Confinement pursued with the development of new sufficient power is now complete. We models for the calculation of cavity have also constructed a cooled J.-P. Connerade, C. Garcia-Segundo, resonances in metallofullerenes, and vacuum cell capable of providing a and A. J. Smith for their interactions with the atomic sample of D2 with most of the molecules structure of the confined atoms. initially in the ground vibrational state. Our experiments on the study of Confinement at the centre of a spherical Rydberg atoms in crossed electric and fullerene cavity effectively isolates an We are also working on the devel- magnetic fields have led to the atom from its environment, and this opment of high efficiency schemes for successful introduction of a new, single- type of atoms exhibits properties of frequency up-conversion to short mode narrow linewidth, tunable pulsed relevance to a number of situations wavelengths that employ maximal OPO system with a resolution much in solid state and in surface chemistry. atomic coherence between the ground superior to the dye lasers used previ- Indeed, confined atoms have even and highly excited states. In a ously. With this advance, we have been been proposed as a path towards the collaboration with the University of able to repeat our earlier study of the realisation of a solid-state quantum Kaiserslautern in Germany we have barium atom in crossed fields with much computer. Of particular interest in this recently demonstrated enhanced superior detail. The improvement is connection is the behaviour of electron conversion in the production of impressive, although a precise figure spin for the confined system. For a coherent 71 nm radiation from Kr atoms. for the resolving power of the new laser proper treatment of this, relativistic The limits set to such schemes from still needs to be extracted from the modelling is desirable. A fully photoionisation have also been explored data. These experiments are relevant to relativistic extension of our work is theoretically in a collaboration with the Ôquantum chaologyÕ because Rydberg in hand. The work is performed in University of Siena in Italy. We find two atoms in crossed electric and magnetic collaboration with researchers in the processes that limit the size of the fields provide a quantum system USA, Russia, Thailand, and coherence depletion of the neutral atoms whose underlying classical dynamics is Uzbekistan. as a direct result of the photoinisation, chaotic. We continue to collaborate and collisional dephasing of the with a group in China on the construction We have continued to develop a coherence that is a consequence of of a similar experiment in Wuhan, with detecting mirror system whose the interaction of the unionised atoms support from the Royal Society and function is enhanced by the plasmon with the photoelectrons (see Figure 3). the Chinese Academy of Sciences. properties of the front reflecting The latter effect is more significant surfaces, and a patent application under normal circumstances. From Our work on atomic clusters has has been filed, jointly between our calculations we have identified continued with the development of a Imperial College London and the strategies that limit the detrimental new theoretical formalism to represent Shimadzu Research Laboratories effects of the electron collisional the multiphoton excitation of plasmons. (Europe) Ltd. 30 Space and Atmospheric Physics http://www.imperial.ac.uk/research/spat

Head of Group: in August 2002 and began sending understanding the fine-scale structure Professor J. E. Harries back high quality images of the Earth in of the Sun's corona. Guided by data December 2002 (see cover). from the SOHO spacecraft, we are The Group carries out research in developing models of the Sun's corona three closely related areas. The first GERB-3 has now been calibrated in that indicate that it is comprised of many is the physics of the Solar interior and our sophisticated Earth Observation small high-density strands, with only atmosphere, including the ionised and Calibration Facility. During 2002 a very small volume actually filled magnetised outer atmosphere of the measurements of radiative fluxes in with plasma at any given time. Sun. The second is the study of the the far infrared red, in the upper tropos- Heliospheric Research extension of the solar atmosphere as phere have been made successfully the solar wind into interplanetary space, by our TAFTS (Tropospheric Airborne A. Balogh, P. Cargill, R. J. Forsyth which forms the local environment of Fourier Transform Spectrometer), and T. S. Horbury the planets of the solar system. The during a campaign in Australia. third is the physics of the EarthÕs Solar Physics We use observations made by our neutral atmosphere and the role it magnetometer onboard the Ulysses plays in the climate system, including P. Cargill and M. J. Thompson spacecraft to study the three-dimen- the interactions between solar sional structures and dynamic processes radiation and the atmosphere. This research programme is directed that occur in the vast volume of space at understanding the physics of the surrounding the Sun. Ulysses is the In the past year, we have continued SunÕs interior and atmosphere. In only spacecraft exploring the regions to receive exciting new data from particular we are interested in uncovering over the Sun's poles and, now in its the four- spacecraft Cluster mission, those dynamical processes that play a 13th year, it has provided us with a allowing unprecedented insights into key role in the SunÕs 11-year magnetic comprehensive collection of data both large and small scale processes cycle and the solar activity that affects covering a complete 11 year solar at work in the EarthÕs magnetosphere. the Earth and near-Earth environment. activity cycle. Our magnetometer onboard the Ulysses space probe has continued One tool is helioseismology, the seismic Analysis of solar energetic particle to make observations over the SunÕs study of the solar interior using acoustic data from our Anisotropy Telescope poles, exploring quite unknown regions waves that propagate through the particle detector on Ulysses have of the Solar System. In the far reaches solar interior. We have studied temporal revealed large delays in particles of the Solar System, the Cassini variations of the SunÕs internal rotation, reaching high heliographic latitudes. spacecraft, which also carries a revealing that the convective envelope This finding challenges current models magnetometer produced by our Group, is involved in such solar-cycle variations of energetic particle propagation, and will reach Saturn in July 2004: it at all depths and latitudes. We are suggests that cross field diffusion is continues to observe the interplanetary also developing local helioseismic more important than previously thought. medium as it travels. Having built the techniques based on time distance magnetometers for these spacecraft, tomography and waveform analysis On the theory side, we are continuing and seen them sent deep into the for studying subsurface flow and the to model interplanetary coronal mass Solar System, we are now exploiting structures beneath sunspots. ejections (CMEs). Our research has the magnetic field observations made. focussed on understanding how In solar physics, observations have We have continued our longstanding these structures interact with the revealed interesting solar latitudinal collaboration with US scientists on solar wind, through both aerodynamic variations in the properties of the sub-surface shear zone.

In the area of atmospheric and climate research we have continued to study the radiative properties of the EarthÕs atmosphere and climate, exploiting data from Earth-orbiting satellites, and powerful theoretical models. We are the principal scientific team responsible for a new satellite radiometer, the Geostationary Earth Radiation Budget (GERB) experiment, which was Figure 1. Variation of the SunÕs internal rotation over 6 years, relative to the first year successfully launched on the Meteosat from MDI data (SOHO satellite). Converging bands are the torsional oscillations; Second Generation Satellite (MSG-1) there are also significant variations at high latitudes. 31 drag and magnetic reconnection. It collection of Nature papers as a result indicates that in the right solar wind of this unique dual spacecraft oppor- conditions, CMEs can survive to tunity. This work clearly showed the large distances in the solar wind. influence of the solar wind on the workings of the magnetosphere of Planetary Plasma Physics Jupiter and revealed the magnetos- M. K. Dougherty and A. Balogh phere in a state of transition from an inflated to a much smaller state. In Our work in this area has concentrated addition clear solar wind control of on understanding the physical radio and auroral emissions were processes arising in the giant planet observed. A pulsating auroral X-ray magnetospheres, that of Jupiter and hotspot on Jupiter was also observed Figure 3. Sketch of an hot, expanding Saturn. We are the Principal Investigator during this period which seems to bubble of plasma, upstream of the institute for the dual technique be driven by internal processes Earth's bow shock, developed from an magnetometer onboard the NASA/ESA within the magnetosphere itself. analysis of Cluster field and particle data. Cassini orbiter which will reach Saturn in July 2004 for the start of its four- The Rosetta probe will perform the first interplanetary magnetic field. Particles year orbital tour. Part of our preparation ever in-depth study of a comet nucleus, are energised and channelled along for the Saturn magnetospheric obser- and will observe the development of the discontinuity, causing a rapidly vations to come consists of careful activity as the comet approaches the expanding bubble of hot plasma. analysis of the previous data sets Sun. Our Group provided the data- Figure 3 is a sketch of an HFA obtained by the Pioneer and Voyager processing unit for a suite of sensors encounter derived from Cluster flybys of Saturn. This has revealed to measure plasma properties and is magnetic field data, in collaboration that accurate modelling of the current one of the six Principal Investigator with the plasma instrument team, sheet at Saturn requires taking account teams which comprise the Rosetta showing the sizes and orientations of temporal variations related to the Plasma Consortium. These sensors of structures within the event. condition of the magnetosphere (which will study the interaction of the cometÕs is dependent on solar wind conditions), tenuous mixed atmosphere of dust, gas Another focus has been on the as well as non-axisymmetric contribu- and plasma, with the solar wind. Due to magnetospheric polar cusps, regions tions due to local time effects. This the launch postponement, ESA will soon that provide the easiest access of will be very important during Saturn target the mission towards a new comet. solar wind energy to the auroral regions. We have played a leading Orbit Insertion and subsequent close Solar Terrestrial Physics approaches to the planet when we role in investigating these poorly will resolve the higher order moments A. Balogh, P. Cargill and T. S. Horbury understood regions of space, and of the internal planetary field, thereby have shown that they are highly allowing us to gain an understanding Analysis of data from the Group's dynamic, moving around apparently of the interior of the planet itself. magnetometers flying on the four in response to changing interplanetary Cluster spacecraft, launched in July conditions, and have totally different The Cassini flyby of Jupiter in late and August 2000, continues to be a structures when viewed in the plasma 2000 whilst the Galileo spacecraft was major activity. and magnetic field. in orbit around the planet resulted in a Physics of the EarthÕs Atmosphere Research has focussed on the three dimensional aspects of the structure J. D. Haigh, R. Toumi and J. E. Harries of boundary layers in the magneto- sphere and solar wind. The structure This research programme is directed of the bow shock as been shown to be at understanding the physics of the intrinsically three dimensional, with the EarthÕs neutral atmosphere and the range of scales that leads to plasma role it plays in the climate system. thermalisation being a considerably The general circulation, composition more complex process than had been and energy balance of the atmosphere previously believed. Using the are determined by a combination of "curlometer" technique, the electric fluid dynamical, radiative and chemical currents associated with the bow factors. We can investigate this using shock have also been measured for observations (from satellites, airborne Figure 2. A Hubble Space Telescope the first time. and ground-based instruments) and image of the planet Jupiter as the space- with theoretical models. We are craft Cassini flew by enroute to Saturn. A recent study has examined hot particularly interested in how electro- It shows auroral ultra-violet observations flow anomalies (HFAs): explosive magnetic radiation is transferred by and a hot spot in the X-rays which were disturbances to the bow shock, caused the atmosphere and how measure- linked to our upstream solar wind magnetic ments of the EarthÕs radiation field field measurements by a change in the direction of the 32 In collaboration with the Complex variability of the spectrally integrated Systems Modelling Group (Department outgoing longwave radiation (OLR). of Earth Sciences and Engineering) We are using wavelet analysis of we have developed a new model for time series of OLR data to examine calculating 3D scattering of radiation for the first time the changes in within inhomogeneous cloud. In an quasi-periodic behaviour with time. atmospheric physics context the model We are also ÔslicingÕ the OLR in is unique and is now being used to different energy bands. This allows Figure 4. Radiation field within an study how cloud structure affects the us to gain a measure of different inhomogeneous cloud layer calculated Earth's radiation budget. cloud processes and how they vary using the 3D scattering code. The colour in space and time. Specifically we Earth Observation and Data Analysis indicates the scalar intensity of radiation are examining the El Nino-Southern at each gridpoint. J. E. Harries, J. D. Haigh and R. Toumi Oscillation (ENSO), and the can reveal information about atmos- Madden-Julian Oscillations, of the pheric structure and composition. Mountains are particularly vulnerable to tropical Pacific and Indian oceans. Conversely we also use information changes in climate. Dramatic reductions These results may provide further on the composition of the atmosphere of glaciers have been observed. Other signals of how our climate is changing. to estimate changes in the radiation changes in the mountain weather are Atmospheric Instrumentation balance and thus to indicate potential highly uncertain due to a lack of data. Development - Space and Airborne climate change. We will be making measurements of Observations atmospheric pressure on a mountain This year we have used our previous to give us information about the local J. E. Harries, R. Toumi and J. Pickering results from satellite data, that showed and large scale flow and is also a direct that water vapour concentrations are measure of the average temperature In the radiative energy balance of the increasing in the lower stratosphere, below the mountain. The Himalaya (and Earth, a considerable fraction (20-35%) to calculate the radiative forcing of Mt. Everest) are of particular interest of the total cooling to space in the these trends, i.e. to what extent the as observations there will allow us to infrared derives from water vapour changes in water vapour might influence study the upper air during the Indian in the upper troposphere in the far the climate of the lower atmosphere. Summer monsoon and the fast winds infrared. We have developed the We have found a signal of the same of the jet stream in Winter. Our Tropospheric Airborne Fourier Transform magnitude, but in the opposite sense, barometer will give us the first high Spectrometer (TAFTS) to measure as that due to stratospheric ozone frequency (five minute resolution) radiative fluxes at different levels decreases. We have also been looking data for this important region. Figure within the troposphere, and to use at the formation of contrails by aircraft 5 shows the team after they placed these data to test climate models in over Europe. Contrails are thought our instrument on the South Col of this very sensitive part of the atmos- to have a warming effect on the climate Mt. Everest at 8000 m. phere. As part of the EMERALD 2 and their formation probability is international collaboration to look at strongly affected by the ambient water Spectrally-resolved measurements the radiation, micro-physical and vapour and temperature. We have of the infrared spectrum of energy dynamics of tropical cirrus cloud quantified, using climate and aircraft escaping to space have shown, for production from deep convection events, simulation models, the effect of flying at the first time, direct evidence of a TAFTS was carried on flights from lower altitudes to reduce contrails. change in global greenhouse forcing. Darwin Australia during November 2002. CO2 emission would increase but the Further studies including cloudy skies effect of contrails could be removed, indicate another exciting possibility: The Geostationary Earth Radiation giving a net reduction in the warming changes appear to account for a Budget experiment (GERB) is designed effect of aircraft. significant signal in the outgoing IR to make highly accurate measure- spectrum, though the signal is confused ments of the reflected short-wave and We have been using computer by sampling uncertainties. In related emitted long-wave infrared radiation simulations to study the response of work, we have studied the time for the first time from geostationary the atmosphere to increases in solar orbit. We have calibrated the first ultraviolet radiation and to large volcanic three instruments (GERB-1,-2 and -3) eruptions. We have shown that the in our Earth Observation Calibration initial effect of both these phenomena Facility (EOCF) and are continuing is to heat the lower stratosphere and to analyse the calibration results. that subsequently this causes a change The first GERB instrument is now in in the general circulation of the lower operation, and an analysis and atmosphere. These sorts of studies are assessment of the initial data are very important for separating natural being made. atmospheric variability from that Figure 5. On the South Col of Mt. imposed by human activity. Everest at 8000 m 33 Theoretical Physics http://www.imperial.ac.uk/research/theory

Head of Group: the resummations required to get domains after phase transitions that Professor K. Stelle results are very complex. Influenced mimic those of QFT. The first of by Luttinger liquids, where duality these experiments, to measure Our work spans a varied set of research provides a natural resummation, we topological defect densities, has been areas with the problems of gravitation have used duality to calculate performed with remarkable success, and its interactions with other matter conductance in a hot relativistic plasma. and a second has been proposed. and forces as a central theme. As a further application of non- perturbative methods, the linear delta Related research has addressed Thermal and Stochastic Theory, expansion has been successfully how topological defects can arise as Particles and Phase Transitions applied to the phase structure of classical objects from the basic quantum scalar fields at finite density, a dynamics. The monopole mass can be M. Blasone, D. C. Brody, T. S. Evans, calculation not amenable to the shown to provide an order parameter H. F. Jones, T. W .B. Kibble, usual lattice Monte-Carlo methods, in gauge theory. Extensive work has F. Lombardo, L. Pogosian and and to the slow rollover problem been done on solitons in SU(N) R. J. Rivers which forms the basis of inflationary models. We found (N+1)/2 distinct theories of the early universe. classes (ÒgenerationsÓ) of kink The recent evidence for neutrino solutions in an SU(N)´Z2 field theory oscillations is perhaps the most In the context of slow-roll models, and identified their stability properties. important particle physics discovery we have also examined the onset of We also looked at the space of SU(5) ± 0 since that of the W and Z . A problem classical behaviour, an a priori monopole solutions and found an with neutrino mixing is the construction assumption in much of cosmology. exact triplication for n=1 monopoles. of the unitarily inequivalent Hilbert The main result is that, in general, In the context of the dual standard spaces on which the corresponding classical behaviour has taken over model this hints at a possible expla- field operators have to act. The original even before the transition is complete, nation of the origin of three families Pontecorvo formula is too naive. We and naive stochastic classical of particles in the Standard Model. have calculated an oscillation formula analysis is valid. As a further ingre- in space, suitable for making direct dient in our understanding of classical In the area of stochastic quantum connection with experiments, and behaviour, we have shown that the mechanics we obtained exact analytic which exhibits corrections to this limiting procedure used by 't Hooft in formulae for the dynamics of the wave formula. obtaining truly quantum systems from function and associated physical deterministic ones amounts to a group observables. This is one of the most More formally, the control of infinities contraction. We have proposed new exciting developments in the subject, in QFT is of central importance and deterministic models which map onto and we are now able to carry out an approach using zeta-function the quantum harmonic oscillator. simulation studies for the time regularisation is central to most evolution of the wave function of any calculations in curved space-times. In parallel, we have begun to solve quantum system. We have also We have shown that zeta-function stochastic equations numerically, to extended the stochastic approach to methods leave extra terms which look at the consequences of multi- study the feasibility of nonlinear make the extraction of physical plicative noise, inevitable in non- quantum systems. Finally, it is known predictions much more difficult, if not equilibrium QFT. In a related activity, that, if the Hamiltonian of a system is effectively impossible. we have developed non-equilibrium invariant under space-time reflection methods for the dual worldlines that symmetry, then it may possess a Current uses of field theory in the can be used to characterise transitions. real spectrum. We have constructed early universe and heavy-ion collisions quantum theory based on such a require Thermal Field Theory - a Stochastic classical equations are also Hamiltonian, showing the self- description of systems at high used to describe non-equilibrium adjointness of such complex, non- temperature and density which may behaviour in condensed matter Hermitian Hamiltonians. In particular, well be out of equilibrium. In such systems. A very fruitful approach is we found a previously unknown circumstances non-perturbative to ask the questions of condensed symmetry in quantum mechanics, methods are obligatory, and our work matter systems that we would of which has the interpretation of a implements these in a wide variety fields in the early universe and make charge operator, whose properties of applications. predictions that can be confirmed by are yet to be explored fully. experiment. To this end we have As one important application, linear proposed experiments with annular response theory is used to estimate Josephson Junctions to test causal transport coefficients in plasmas, but scaling bounds on the production of

34 Quantum Gravity and the Causal set theory has also been the One of the most important recent Foundations of Quantum Mechanics subject of much study by Garcia and developments in theoretical high collaborators. In particular, they have energy physics is the AdS/CFT J. Halliwell, C. Isham, K. Savvidou constructed a classical stochastic correspondence. Recent work has and L. Smolin growth model in which the partial been aimed at generalising this to order is formed sequentially through theories with less supersymmetry or The decoherent histories approach to classical probability rules. A key step to non-conformal theories, which are quantum theory continues to be an is the construction of a measure on much closer to realistic models. The important focal point for much of the the space of causal sets: this measure main focus of our work in this area work in the group on quantum could also be a key ingredient in has been the study of fractional 3- mechanics and quantum gravity. applying quantum category theory to branes on conifolds, which are dual This approach has proved hugely give a quantum theory of causal sets. to a class of confining N=1 super- useful in discussing emergent classi- symmetric gauge theories. cality in quantum mechanics and for In connection with both of the dealing with situations which involve endeavours mentioned above (ie, Resolution of singularities has also time in a non-trivial way. `discrete quantum spacetime structure' been studied at the supergravity level and `causal set theory'), Raptis, in through an analysis of asymptotically Some aspects of our work on the collaboration with Zapatrin, has worked conical spacetimes with Heisenberg decoherent histories approach connect on a combinatory-algebraic approach symmetries. These solutions gener- with the field theory side of the group, to quantum spacetime topology. He alise the Eguchi-Hanson metric, and discussed above. We have shown has also been collaborating with Mallios, we are in the process of applying that the deterministic quantum theory on applications of the latter's sheaf- them to dimensional reductions on of 't Hooft provides a useful arena in theoretic Abstract Differential branes in infinite transverse dimen- which to investigate the relationship Geometry to causal sets and discrete sions for cosmological applications. between exact and approximate Lorentzian quantum gravity. The decoherence. This in turn is related to algebraic structures involved have While most of the previous investiga- some of our work on hidden variable been also applied to certain structural tions of the AdS/CFT duality were theories in quantum gravity. Also, earlier issues in quantum computation and based on a supergravity approximation, work on the relationship between networks theory. string alpha-prime corrections also decoherence of histories and infor- encode important information about mation storage in the environment There has been much work on the the strong-coupling expansion on has now been extended to the case application of the consistent-histories the gauge theory side. We have of decoherence by scattering, and approach to quantum theory in the investigated the effect of the leading this turns out to be expressed most context of quantum field theory and string corrections to the supergravity naturally in the language of non- quantum gravity. In particular, low-energy effective action for a 3- relativistic many body field theory. Savvidou has developed a history brane/conifold solution. We also gave a version of quantum field theory, which general argument that supersymmetric Activity has continued in developing has been extended by Isham and solutions solving BPS conditions at the use of topos theory in theoretical Savvidou to include the quantisation the supergravity level continue to physics. In particular, Isham and of the foliation vector. However, the satisfy a 1st order renormalization- collaborators have considerably most important advance has been group type system of equations with extended their earlier work on the Savvidou's construction of a history extra ``source'' terms encoding the construction of a topos perspective, theory of general relativity, which string corrections. with an associated contextual logic, offers the possibility of a new, space- on the Kochen-Specker theorem in time based approach to quantum Another important direction of research quantum theory. The theory has now gravity and quantum cosmology. in string theory is the investigation been generalised to incorporate the String Theory, M-Theory and String of mechanisms for supersymmetry most general type of quantum theory. Cosmology breaking and the stability of non- supersymmetric vacua. Useful insights Theories of discrete space-time S. Alexander, A. Fotopoulos, are gained by the study of exactly structure are being studied from a M. Majumdar, K. Stelle and A. Tseytlin solvable string models such as on variety of perspectives. In particular, Melvin magnetic flux tube backgrounds. Isham has just completed the first of Our research in recent years has been We have shown how to reformulate a series of papers on a completely on various aspects of string theory; the problem of the closed string new way of constructing quantum in particular on the gauge theory-- (winding mode) tachyon instability in theories of causal sets, space-time string theory connection and on terms of the instability of a related topology, and other such structures. string theories in curved Ramond- gravitational background. This allows This is based on a new subject - Ramond backgrounds and their one to consider its evolution purely quantum category theory - that he is application to the description of in field-theoretic terms. We have developing for this purpose. gauge-theory dynamics. also found generalisations of the 35 Melvin model that preserve a fraction of AdS have logarithmic dependence prevent this from happening. supersymmetry for special choices of on spin not only at the classical parameters. These models can be string level but also when including Quintessence is a popular expla- viewed as continuous-parameter quantum string corrections. nation for the acceleration of the analogs of non-compact orbifold models Universe. One may then ask what and can be used to study the dynamical In M--theory, the antisymmetric tensor are its implications for theories of flow between supersymmetric and gauge transformations have a topolog- galaxy formation and CMB anisotropies. non-supersymmetric vacua in string ically non-trivial extension that probes This question was tackled in great theory. the cohomology of the underlying detail by our Group, in the context of spacetime and which is intimately various coupled and uncoupled A new development during the last related to the charge spectrum of quintessence scenarios that we year has been the extension of the branes. We have studied the relation originally proposed. The Group also AdS/CFT correspondence to the between bulk and worldvolume forms investigated the possible interactions string theory level using a special of these using relative cohomology, of a quintessence field and the large R-charge limit suggested by showing how the large gauge trans- formation and evolution of super- Berenstein, Maldacena and Nastase. formations are preserved by the massive black holes. It was proposed The corresponding string theory is anomaly-cancelling mechanism of M - that supermassive black holes may defined in a maximally-supersym- theory. be primordial black holes that have metric plane-wave background. eaten too much quintessence. Using light-cone gauge, we have Brane-world models offer an approach found explicitly the spectra of string to cosmology from string theory. Over the past two years our Group theories in plane-wave backgrounds We have pioneered the study of was instrumental in establishing a 5 which are limits of AdS5´S and Horava-Witten geometries in D=5 framework for relating the theory 3 AdS3´S . spacetime. We have studied the and observations of a varying fine dynamics of the radion mode involved structure constant. Our work has led Supergravity plane-wave solutions in inter-brane forces and the possible to a large literature exploring the exist with varying amounts of unbroken potentials that could arise for this different implications of a varying supersymmetry. We have clarified how mode. We have studied models alpha in all sorts of astronomical and the worldvolume picture corresponds incorporating brane gasses in the laboratory contexts. The Group also to the supergravity bulk picture early universe that may provide a has related these observations to the through a comparison of unbroken dynamical mechanism for the four- current acceleration of the universe, worldvolume supersymmetry in dimensionality of observable showing that acceleration tends to physical and in light-cone gauges. spacetime. We have also studied stabilise time-varying constants, possible mechanisms for inflation thus relaxing many observational Relations between supergravity and arising from D-brane annihilation. constraints. Implications for CMB super Yang-Mills have been clarified Cosmology and Varying Constant anisotropies were also studied by in a study of the divergences of Theories several members of the group. maximally supersymmetric theories. Finally, we showed how thermal Differences between unitarity-based S. Alexander, R. Bean, T. W. B. Kibble, fluctuations in varying speed of light predictions of the order of onset of J. Levin, J. Magueijo, M. Parry, and (VSL) scenarios could produce the ultraviolet divergences and the L. Pogosian right spectrum for explaining CMB predictions of standard superspace fluctuations and galaxy clustering Feynman diagram analysis have The cosmic microwave background properties. now been resolved in the maximal (CMB) is a unique tool for testing super Yang-Mills case. The difference theories of the early universe. One One of the highlights of the Group's disappears when one employs an of the major predictions made by research was the discovery that N=3 harmonic superspace formalism structure formation theories is that varying constant theories, and in of the N=4 theory. Although there is the CMB density fluctuations should particular VSL theories, may play an not so far an analogous N=7 formu- be Gaussian. Imperial has played a important role in the quantisation of lation of maximal N=8 supergravity, leading role in the quest for methods gravity. Our work on the non-linear there is a hint that such a formulation for testing this hypothesis. Besides the realisations of the Lorentz group has might exist. development of data analysis software triggered much subsequent work on in collaboration with investigators at methods for implementing invariant We have developed (extending work Cambridge MRAO, and CITA, we quanta of space and time. But, more of Gubser, Klebanov and Polyakov) analysed a number of actual datasets, interestingly, it was shown that such a semiclassical approach to the most notably the Maxima-Boomerang VSL quantum gravity theories may quantisation of closed strings in dataset. The Group hopes to keep explain the presence of ultra high 5 AdS5´S , demonstrating that the this leading position when MAP data energy cosmic rays. This could open anomalous dimensions of operators is released in the very near future, the door to observational quantum corresponding to rotating strings in though shortage of manpower could gravity. 36 Undergraduate Teaching http://www.ph.imperial.ac.uk/ug

Director of Undergraduate Studies: develop their knowledge and under- Occasional Students Professor A. R. Bell, Dr R. C. standing of Physics to a level which Thompson (from September 2003) equals or exceeds that offered by Each year about thirty students from any other university in the UK. We universities throughout Europe and Senior Tutor: Dr R. J. Forsyth are carrying out a major review of further afield come to study in the Admissions Tutor: Prof. W. G. Jones our programmes to ensure that they Department for selected final year School Liaison: Dr J. Hassard are up-to-date and meet changing courses and laboratory work. Most expectations regarding international come under ERASMUS/SOCRATES The Blackett Laboratory, the largest (particularly European) standards. exchange student programmes. Physics Department in the UK, The Departmental Staff/Student These Occasional Students, and welcomes about two hundred new committee is very active and makes those European and International undergraduate students each year. an important contribution to the students enrolled on our three and We offer three year and four year design of the curriculum and to four year degree programmes, undergraduate degree programmes continuing improvements in teaching. greatly enhance the cosmopolitan designed to match the pre-university ethos of the Department. experience of students from the UK, All programmes start with a firm MSci or BSc? Europe and overseas. These degree foundation in core physics and ? programmes lead to either the BSc mathematics followed by a broad Broadly speaking, students aiming for or the MSci degrees of the University and flexible range of options in the a career as a professional physicist of London (under special regulations later years. Courses are lectured by or wishing to understand physics at for Imperial College). experts in the field, and the breadth the frontiers of research should follow and depth of research activity in this the MSci programme both for the The Degree Programmes large department enables us to bring additional content and also for the students to the frontiers of research opportunity to develop professional Entry is onto five degree programmes, in a wide range of specialities in skills and undertake a major project. and the course structure allows easy physics. The department received The MSci is the normal route to a transfer between most of the the top grade of 5* in the 2001 PhD. The BSc is aimed at a wide programmes in the early years. research assessment and a teaching variety of students who wish to quality assessment of ÔexcellentÕ. follow careers outside specialised Three Year Programme The lecturers are drawn from our research. Many employers value the nine internationally recognised numeracy and problem-solving skills BSc Physics research groups: of Physicists. For example, many physics graduates find their degree ¥ Astrophysics Four Year Programmes an excellent platform for a career in ¥ Condensed Matter Theory finance. Some students choose the ¥ Experimental Solid State BSc Physics with Studies in three year BSc as a rapid and less ¥ High Energy Physics Musical Performance extended route into careers based ¥ Photonics on physics in industry and public MSci Physics ¥ Plasma Physics service. Others aim for a research ¥ Quantum Optics and Laser Science MSci Physics with a Year in career in physics by taking the BSc ¥ Space and Atmospheric Physics Continental Europe followed by a specialist MSc. ¥ Theoretical Physics. MSci Physics with Theoretical First Year Courses We also draw on expertise in other Physics departments to offer Mathematics Courses in the first year cover:- and Biophysics courses. Final year The Department also offers a four ¥ Electricity & Magnetism projects are offered in all these year BSc in Physics with a Year in ¥ Mechanics research areas, providing an oppor- Continental Europe, and a three year ¥ Relativity tunity for students to work alongside BSc in Physics with Theoretical ¥ Structure of Matter academic staff, research fellows, Physics, but students are not normally ¥ Vibrations & Waves research assistants and postgraduate admitted to these programmes in ¥ Quantum Physics research students. In the first three Year 1. ¥ Professional Skills for Physicists years, students receive tutorials in ¥ Mathematics I groups of four from academics and The Department aims to provide all ¥ Mathematical Physics Theory other researchers. students on all degree programmes ¥ Physics Laboratory I with courses of the highest quality ¥ Physics Short Experiments and giving students the opportunity to Project I 37 Weekly seminar groups are a novel waves, radioactivity, solid state, ¥ Music and ideas in the nineteenth feature of the first year. These include operational amplifiers and computing. century group projects, development of Emphasis is placed on the development ¥ Macro-economic policy problem solving skills, and explo- of a range of experimental techniques ¥ Accounting and finance ration of research articles, web sites as well more general professional MSci Fourth Year and research data. skills such as writing reports, keeping a laboratory note book, and In their fourth year MSci students In the First and Second Years we error assessment. complete a major project with a teach computing in C++, a valuable research group. This gives students The Third Year skill which is attractive to future an opportunity to get to grips with an employers. During the first few weeks MSci candidates take core courses in:- extended project that lasts the whole of the first term students are given a year and relates to current research ¥ Nuclear and Particle Physics four hour Òhands-onÓ introduction to activities. In some cases, the project ¥ Solid State Physics computing and current application results in the publication of a research ¥ Atomic and Molecular Physics packages. paper. Under the guidance of a ¥ Professional Skills lecturer, students learn how to set ¥ Laboratory III For most students, the first year goals and plan their work to achieve practical class consists of four week them. They learn to research literature, BSc candidates take Nuclear and sessions on optics, electronics and to design an experiment or develop Particle Physics and at least one of computing. They may then choose computer software, and to present the other core lecture courses. between Maths Physics Theory and their results in oral and written They may take one or two terms of more laboratory. For those choosing presentations. lab, six weeks are spent on short laboratory, and all have to complete a project, which may be laboratory experiments designed to complement The project is coupled to the or library based, or theoretical. the first year physics lectures. The Research Interfaces course which majority of students then carry out a develops professional skills. Both MSci and BSc candidates project working in small groups culmi- This course explores the subjects of complete their third year with a nating in two open days in which staff, project management, written selection of Level 3 options. The other students and sixth-formers view communication, financial management more theoretical physics lecture poster presentations on their project. and spoken communication. An aim is courses are marked with a (T) :- to give students a working knowledge The physics lecture courses are ¥ Computational Physics (T) of the vocabularies relating to examined during the third term. ¥ Group Theory (T) research in universities and industry. ¥ Dynamical Systems & Chaos (T) The Second Year ¥ Condensed Matter Theory (T) At present, students choose two Second year core courses cover:- ¥ Instrumentation further option courses from a list of eighteen options and select three ¥ Quantum Mechanics I ¥ Astrophysics options Òwith advanced studyÓ. ¥ Thermodynamics ¥ Plasma Physics Following the present curriculum ¥ Statistical Physics ¥ Molecular Biophysics review, affecting the fourth year in ¥ Mathematical Physics ¥ Lasers, Optics and Holography 2004-05, MSci students will choose ¥ Electromagnetism ¥ Advanced Classical Physics a selection of Level 4 options, and ¥ Electrons in Solids may select one Level 3 option (see ¥ Optics Students may also choose up to one above). The Level 4 options will be :- ¥ Applications of Quantum Mechanics Level 2 option (see above) and up to one Level 4 option (see below). ¥ Statistics of Measurement ¥ Biophysics of Nerve Cells & They may also include one of the ¥ Professional Skills seminars Networks following courses:- ¥ Physics Laboratory II ¥ Space Physics ¥ History of science ¥ Devices BSc and MSci Physics candidates ¥ History of technology ¥ Optical Communications choose a Level 2 option from:- ¥ Philosophy I ¥ Quantum Optics ¥ Cosmology ¥ Sun, Stars and Planets ¥ Modern literature and drama ¥ General Relativity ¥ Physics Applied to Medicine ¥ European history ¥ Atmospheric Physics ¥ Mathematical Methods ¥ Politics ¥ Photonics ¥ Language ¥ Communication of science (practical) ¥ Science, communication and society ¥ Particle Physics (T) ¥ Quantum Field Theory (T) Second year laboratory work includes ¥ History of medicine ¥ Unification (T) experiments on spectroscopy, ¥ Ethics of science and technology ¥ Computational Physics (T) diffraction and holography, interfer- ¥ Roman history ¥ Quantum Statistical Physics (T) ometry, transmission lines and thermal ¥ Art and nature 38 MSci Physics with We have established links with host Physics with Studies in Musical Theoretical Physics universities in France, Germany, Performance Italy, Spain and Switzerland. These Students who choose to follow this are: UniversitŽ de Paris XI (Orsay), The musical life of Imperial College four year MSci programme concen- Ecole SupŽrieure de Physique et de has always been strong and many trate on the more theoretical options. Chimie Industriel (Paris), Ecole physics students have demonstrated In their first year they take an extra Polytechnique FŽdŽrale de Lausanne, high ability in musical performance. formal mathematical physics course Institut National Polytechnique de The joint degree programme with instead of project work and in their Grenoble, UniversitŠt Erlangen- the nearby Royal College of Music second year the Mathematical Methods NŸrnberg, UniversitŠt Freiburg, is for physics students who can also option. In Year 3 these students must UniversitŠt Hamburg, Technisches reach the RCMÕs stringent admission take Advanced Classical Physics UniversitŠt Karlsruhe, Universitˆ degli standards in musical performance. instead of laboratory. The fourth year Studi di Padova, Universitˆ degli Studi This programme provides students project is theoretical and they also take di Trento, Universitat de Valencia, with a high quality honours BSc a specified number of theoretical Universidad de La Laguna (Instituto qualification in physics while providing options. de Astrof’sica de Canarias), and musical training to the highest inter- Universidad de Cantabria (Santander). national standards. The music The Year in Europe Programmes component mainly consists in high The MSci in Physics with a Year in Each of these universities has high level performance tuition by the Europe is of four years duration with standing and extensive research Professors of the Royal College of the third year being spent in a activity. Some have exceptional Music but also includes musical research group in a host university facilities in particular research fields. theory and history of music. The in continental Europe. Year in Europe For example, La Laguna is excellent Imperial College Director of Music is students have derived great benefit for Astrophysics because of the actively involved with this course. and enjoyment from this opportunity siting of many astronomical Students on this programme have to widen their experience. They usually telescopes in the Canary Islands. given public recitals, performed as go to Europe on SOCRATES / concerto soloists, and won national ERASMUS exchange programmes. competitions such as Young Musician of the Year. Students are visited twice during their year abroad by a member of staff who normally is very familiar Year in Europe with the host country and university. Host Institutions Students carry out a research project in a research group. They are assessed on their written project report, a report from their supervisor, and an oral presentation in the host language. UNITED KINGDOM Hamburg In addition to the research project, students attend physics lecture courses GERMANY and sit examinations, written or oral, in the host language. As preparation ESPCI for their year abroad they take Karlsruhe Orsay Erlangen FRANCE language courses in both their first Freiburg SWITZERLAND and second years and are recom- Lausanne mended to take Mathematical Santander Grenoble Methods in their second year. Trento Padova ITALY In their fourth year MSci Year in S P A I N Europe students sit the Comprehensive Papers, and take Nuclear and Particle Valencia Physics, the Research Interfaces course and choose from a range of options drawn from the third and La Laguna fourth year programmes. The (Tenerife) research project completed abroad counts as their MSci project. 39 The Comprehensive Papers the employment potential of their universities studying with us for one degree and of the quality of their year as exchange students. The Our degree programmes contain a university experience are much Department is greatly enhanced most valuable and unique component: higher than the European average. through the rich cultural and national the two comprehensive examination diversity of our students. papers. These carefully constructed All applications receive careful Schools Liaison papers are designed to test our attention and those applicants that studentsÕ ability to apply the core appear to be well suited to our School liaison is a high priority physics taught in earlier years of the courses are invited for a visit and within the Department, and we offer course and students are prepared interview. These visits take place in visits to schools and Òguided toursÓ. for this kind of problem solving through small groups between early November We also offer places to a number of special tutorials. Most candidates and early March and consist of a school students undertaking work complete these papers in their third tour of the campus, usually including experience training. We have year. a Hall of Residence, guided by an extended our reach geographically: undergraduate, followed by a meeting for example, Physics has been Undergraduate Admissions with the Admissions Tutor or one of featured in the annual Imperial College Applications for our undergraduate his colleagues on the admissions recruitment visit to Hong Kong. courses are received through the team. This is designed to give UCAS system from all parts of the applicants information about the The Department, in association with world although most are from the UK. courses and the facilities and also the College and the University of We wish to encourage applications about life in Imperial College and London, has an extensive range of from all sectors, particularly from areas London. There is then a tour around out-reach programmes. These are traditionally under-represented in the department followed by a short free and are designed to introduce higher education and from other individual interview. The latter helps physics to potential undergraduates. European countries. We are looking us to get to know the student as an The most popular is the Open Day, for students of high ability and individual and is mainly concerned focussed around a display by First motivation with the potential to do with interests and motivation. It also Year students of their project work, well on our courses. Offers of enables applicants to raise questions and held around the third week of places are conditional on achieving of particular interest to them. June. There are also various high grades in physics and mathe- Masterclasses held at various times matics at A-level and in a third subject. Our high international profile is during the year. The highly popular The average of the grades of students manifested in many ways, not least two-day Women in Science and admitted is significantly above AAB through our membership of several Engineering courses, held in July, (best 3 A-levels). We also admit strategic alliances with major univer- are specifically designed to students offering the International and sities in Europe (e.g. CLUSTER and encourage women students to European Baccalaureate, French the IDEA League) and with the consider a degree course in one of Baccalaureate, German Abitur, US presence of large numbers of the science or engineering disciplines. Advanced Placement examinations students from other European and school leaving qualifications from many other countries.

The percentage of women under- graduates admitted onto our course has increased over recent years and in 2002 was over 26%, which significantly exceeds the national average. This increase has been helped by the CollegeÕs ÔtasterÕ courses called WISE (Women into Science and Engineering) which we operate in July each year.

Our students have wide interests and abilities, particularly in music, the arts and sports, as well as being among the most talented in the land in physics. They go on to a wide variety of careers after graduation

and a recent European wide survey Photo: Meilin Sancho has indicated that their rating of both Undergraduate student projects on display at the first year studentsÕ Open Day. 40 Postgraduate Studies http://www.ph.imperial.ac.uk/pg/

Director of Postgraduate Studies: degree in Physics or a related subject. wide range of opportunities in Dr Julia Sedgbeer The usual length of registration for a postgraduate physics. Further infor- PhD degree is three years. mation can be found in the The Physics Department is one of Postgraduate Study in Physics the most prestigious postgraduate In addition to research training, the booklet, (email: schools in Physics in the UK. In terms Department offers postgraduate [email protected]) or on of research it uniquely covers the taught courses leading to the MSc www.imperial.ac.uk/publications/pgb/ most comprehensive range of degree of the University of London General information about graduate important experimental and and the DIC. The Department offers studies at Imperial College London theoretical research fields. These two MSc courses: Optics and can be seen at extend from astronomy, space and Photonics and Quantum Fields & www.imperial.ac.uk/pgoptions. plasma physics to high energy, Fundamental Forces. Further details theoretical and atomic physics. Solid of these MSc courses are given below. MSc in Optics and Photonics state, laser physics, applied optics and photonics have wide applications, The new Graduate School of The MSc course in Optics and while fields such as quantum infor- Engineering and Physical Sciences Photonics has been running since mation theory may lead to exciting (www.imperial.ac.uk/gradeps/) has October 2001 and draws on the skills new applications. There are close been established to develop and of staff actively involved in optics links with the biophysics research enhance the academic experience research. The title reflects the fact group (part of the Department of of graduate students at the College. that the course covers both the Biological Sciences), which is also It provides training programmes and traditional areas of optics, which are housed in the Blackett Laboratory. workshops in professional and other of key importance to the application There are many examples of interna- skills, undertakes quality assurance of optical techniques, and the emerging tional and industrial collaboration of graduate programmes, organises areas of photonics, notably optical involving our nine research groups. events, such as guest lectures and communications. The course aims There are also interdisciplinary centres symposia, and promotes career to provide the professional skills in where researchers from different opportunities for graduate students. optics which are in demand by groups or from different Departments industry and academia. collaborate closely to benefit from each Very few institutions world- otherÕs expertise. The Department has wide are able to offer such a extensive facilities and a tremendous range of research topics available to postgraduate research students.

Information about the research being undertaken in the particular groups and centres can be found under their sections elsewhere in this report; further details can be obtained from the individual Heads of Group (see page 49).

The Department provides facilities and supervision for students to engage in research work leading to a higher degree of the University of London (MPhil or PhD), and to the Diploma of the Imperial College (DIC). About 60 postgraduate research students join the Blackett Laboratory each year, the majority being UK students with about 25% from other EU countries and about 15% from overseas. The normal qualification for acceptance for research training is a first or second class honours

41 There are a large number of job MSc in Quantum Fields and Optional courses: opportunities in optics and photonics Fundamental Forces Supersymmetry throughout the UK and the rest of Cosmology and Particle Europe, not only in optical communi- The Theoretical Physics Group runs Physics cations but also in many other areas this very successful MSc course, Topics in Quantum Gravity of applied photonics. attracting around 15 students annually. String Theory It is normally a one-year course but Differential Geometry The 12-month MSc Optics and can also be taken part-time over two Special Topics Photonics course consists of lectures, years. A series of lecture courses (short specialist courses on laboratory experiments and a project. occupies the year up to May and topics of current interest) In the first term, there are four students spend the summer on a Foundation lecture courses in project leading to the writing of a Available undergraduate courses: Information and Telecommunications, dissertation. The course is intended Quantum Mechanics Imaging, Lasers, and Optical to bridge the gap between under- Group Theory Measurement and Devices. In graduate-level work and the research Dynamical Systems and Chaos addition, there are sessions dedicated frontier in theoretical physics. Many General Relativity to the development of professional successful students have gone on to skills. There are occasional seminars do a PhD either at Imperial College Courses are offered subject to staff on the application of optics technology London or at another major university. availability; certain courses may not in industry, together with seminars Unfortunately, no financial support is be offered in a given academic year. on research and development in available for students attending the universities and industry. In the course. Students are assessed by examina- second term, a number of option tions and a project dissertation. The courses are offered, including The lecture courses currently being examinations are on the compulsory Optical Fibres, Advanced Optical offered are: courses and on four optional courses, Communications, Optical Design, which may include up to two under- Optical Design Laboratory, Optical Compulsory lecture courses: graduate options. Examinations on Fibre Sensors, Laser Optics, Laser Quantum electrodynamics all the courses are held in May. Technology, and Optical Displays. Electroweak unification There are also informal tests on the Advanced Quantum compulsory courses in January. The laboratory experiments cover a Field Theory wide range of subjects and are MSc students are also encouraged spread over approximately 54 half- to attend the regular weekly seminars days in the first and second term. at which visiting speakers present recent research results, as well as The project lasts from mid-May to internal seminars by mid-September, and many projects research students. can be carried out in industry. These are Examples of recent projects are ÒA supple- new method of producing unidirec- mented by tionality in solid-state ring lasersÓ, an inter- ÒPolymer/nanocrystal blends for Collegiate solar cellsÓ, ÒFemtosecond pulse programme of shaper using a spatial light modulatorÓ, weekly ÒAdaptive optics for the human eyeÓ, seminars on ÒMEMS based digital filterÓ, ÒOptical string theory and modelling and optimisation of organic related subjects. LED structuresÓ and ÒFluorescence lifetime imaging applied to microscopyÓ.

There are 20 EPSRC funded places for suitably qualified UK students. Funding is also available to cover the fees for suitably qualified students from other EU countries. Almost 50 companies have backed the course with offers of support in kind equivalent to £1.5M over the five years of funding.

42 PhD Degrees awarded in the R. A. Illingworth ÒDevelopment of Space and Atmospheric Physics Department in 2002 Trigger Software for the silicon and fibre trackers and a study of B L. K. Gohar ÒA Study of the Astrophysics Meson Lifetimes for the D¯ Radiative Contribution to the Entropy Experiment.Ó Budget of the Atmosphere.Ó J. M. L. C. Afonso ÒOn the Star- Supervisor: Dr J F Hassard Supervisor: Prof. J E Harries Forming Properties of Faint Radio Sources.Ó D. Smith ÒAnalysis of the Flavour M. Y. Gulamali ÒSpacecraft Supervisor: Prof. M Rowan-Robinson Changing Neutral Current b sg at Observations of Magnetohydrodynamic BaBarÓ Turbulence in Corotating Interaction A. M. Begley ÒParticle Cascades in Supervisor: Dr J A Nash Regions.Ó Quasar Central Engines.Ó Supervisor: Prof. P J Cargill Supervisor: Prof. J J Quenby Optics - Photonics P. J. Sagoo ÒChanges in the A. Meli ÒParticle Acceleration at Z. Ansari ÒWhole-field, real-time Greenhouse effect of the earth from Relativistic and Ultra-relativistic Photorefractive Holography for measurements of thermal emission Shock WavesÓ Imaging through Turbid Media using spectra in 1970 and 1997Ó Supervisor: Prof. J J Quenby Sources of Diverse Spatial and Supervisor: Prof. J E Harries Temporal CoherenceÓ Condensed Matter Theory Supervisor: Prof. P M W French A. C. Tomsett ÒTime series Analysis of United Kingdom Precipitation and S. Avogadro di Collobiano ÒTangled F. Koch ÒLinear and Non-linear its ExtremesÓ Nature: A Model of Ecological Characterization in Optical FibresÓ Supervisor: Dr R Toumi Evolution.Ó Supervisor: Dr J R Taylor Supervisor: Dr K Christensen Theoretical Physics D. G. Moodie ÒElectroabsorption S. OÕBrien ÒArtificial Magnetic Modulators for Telecommunications M. Asprouli Ò Real Time Effective Structures.Ó Networks.Ó Actions in Quantum Field TheoriesÓ Supervisor: Prof. J B Pendry Supervisor: Dr J R Taylor Supervisor: Dr R J Rivers

R. Vardavas ÒFluctuations and P. C. Reeves-Hall ÒOptical Fibre R. E. Bean Ò Scalar Field Scaling in 1D Irreversible Film Based Pulse Sources and Cosmologies and their Observational Growth Models.Ó Amplifiers.Ó Implications.Ó Supervisor: Prof. D Vvedensky Supervisor: Dr J R Taylor Supervisor: Dr J C Magueijo

Experimental Solid State Physics Optics - Quantum Optics A. Filippi ÒThe Multiplicative and Laser Science Anomaly and Zeta-Function K. A. Yates ÒTransport Properties of Regularization in Quantum Field Colossal Magnetoresistive Materials.Ó E. J. Grace ÒOptimisation of Kerr- TheoryÓ Supervisor: Dr L F Cohen lens mode-locked LasersÓ Supervisor: Dr R J Rivers Supervisors: Prof. G H C New & High Energy Physics Prof. P M W French H. B. Sandvik ÒVarying Fundamental Constants in CosmologyÓ M-L. Aspinwall ÒMeasurement of the I. Kucukkara ÒElectromagnetically Supervisor: Dr J C Magueijo exclusive branching fractions and Induced Transparency in Four Wave Asymetries of B pK at BaBarÓ Mixing Scheme.Ó MPhil awarded in the Department in Supervisor: Dr P D Dauncey Supervisor: Prof. J P Marangos 2002

D. U. Bauer K. J. Mendham ÒEnergetic Cluster 0 Experimental Solid State ÒA study of B s J/yf in the D¯ Explosions in Intense Femtosecond experiment and an example of HEP Laser FieldsÓ P. M. Hudson ÒScanning Probe technology transferÓ Supervisors: Dr J W G Tisch & Microscopy Studies on Colossal Supervisor: Dr J F Hassard Prof. J P Marangos Magnetoresistive Materials.Ó Supervisor: Dr L F Cohen D. Bowerman S. S. Virmani ÒEntanglement ÒStudy of the rare decay B0 p0p0 Quantification & Local Discrimination.Ó at BaBarÓ Supervisor: Prof. P L Knight Supervisor: Dr P D Dauncey

43 Research Grants

The following grants, valued at Chittenden, J; Microscopic X-pinch Sumner, T; Inertial sensor charge over £15.0 million, were initiated plasmas of extremely high density management system for LISA. during 2002. and temperatures: A computational £189,100. investigation. £100,475. Air Products and Chemicals Inc. MoD (AWE plc) Bradley, D; New class of materials Torok, P; EPSRC Advanced Haines, M G and Chittenden, J; for organic light emitting devices. fellowship: Interaction of electromag- The William Penney Fellowship for £31,750. netic waves with complex specimen Dr J Chittenden. £31,200. structures in optical microscopy and Astrium Gmbh conoscopy. £28,029. National Physical Laboratory Balogh, A; Double star magnetic Segal, D; Advanced optical field investigation. £280,955. Bradley, D; Basic Technology: Next flywheel oscillators. £54,098. generation artificial vision systems: Balogh, A; Double star pre- reverse engineering human visual Natural Environment Research integration. £487,797. processes. £240,557. Council Toumi, R; HIMAP: High Himalayan BP International Ltd. Caplin, D; Investigation of the atmospheric pressure. £30,346. Bradley, D, and Jones, T; OSCER- magnetic properties of potential Organic Solar Cell Research. spintronic ferromagnetic materials. Pickering, J and Harries, J; £750,000. £37,550. EMERALD- II Egrett Microphysics experiment with radiation, Lidar and CCLRC Hinds, E; The UK cold atoms dynamics in the tropics. £99,774. Kellock, S; Co-ordinaton of gist network: UKCAN. £49,625. activities of the GERB international Harries, J, Pickering, J and science team. £107,291. Barnham, K; Visiting fellowship for Toumi, R; Measurement of far IR Dr Massimo Mazzer to study Strain- Radiative Spectra and Energy fluxes Commission of European balanced quantum well solar cells. in the atmosphere. £188,644. Communities £60,872. Cargill, P; Theory observation and Harries, J; New methods to simulation of turbulence in space Marangos, J; Modulation of estimate grid or catchment evapo- plasmas. £132,000. femtosecond laser pulses by ration using satellite and ground- molecular coherence. £130,749. based measurements. £156,557. Caplin, D; SCENET 2. £2,000. Phillips, C; Terahertz sideband Harries, J and Toumi, R; The Murray, R; HYTEC. £124,461. generation and quantum cascade global distribution, variability and lasers. £53,482. radiative-climatological impact of Dainty, J C; SHARP-EYE. atmospheric water vapour. £898,993. Bradley, D, De Mello, A and De £141,239. Mello, J; Polymeric detection Pendry, J; Development and systems for micro analysis. Particle Physics & Astronomy analysis of left handed materials £294,748. Research Council (DALHM). £156,568. Bowerman, D; Measurement of the Bradley, D, Jones, T, and Steinke, J; CP unitarity triangle angle alpha Meikle, P; The physics of type IA Carbon based electronics: A through the systematic study of rare explosions. (Type la supernovae). national consortium. £142,921. B meson decays to three pions at £67,941. BaBar. £95,471. Bell, A; Fokker-planck simulations Department Of Trade & Industry of transport and absorption in laser- Britton, D; GridPP project manager French, P; Functional bioimaging produced plasmas. £164,976. costs. £82,012. using fluorescence lifetime imaging. £920,664. European Space Agency Kalkkinen, J; M-Theory solutions Sumner, T; Inertial sensor charge and geometry. £120,394. Engineering & Physical Sciences management system for LISA. Research Council £12,000. Hinds, E; eEDM:Measurement of Hinds, E; Measurement of electron the electron electric dipole moment. electric dipole moment. £40,239. £191,840.

44 Dainty, J C; A complete toolkit for Balogh, A; Research in solar, UKAEA adaptive optics. £341,359. space and planetary physics and Cowley, S; PhD student to work in instrument development at Imperial the field of stability analysis and Rowan-Robinson, M; Infrared College. £1,313,070. diagnostic tools. £43,969. astronomy and cosmology. £900,730. Butterworth, I; Visit by Professor University of Bologna Thomas Ferbel. £13,436. Harries, J; Polarisers for REFIR Thompson, M; Measuring oscilla- Far-IR interferometry. £30,602. tions of nearby stars (MONS). Dainty, J C and McCall, M; Laser £4,033. guide star adaptive optics for the University of St Andrews visible. £132,762. Bradley, D; Ultrafast photonics for Dornan, P; Study of elementary datacomms above terabits speeds. particles and their interactions. Drew, J; ICSTM Astrophysics short £752,195. £2,582,591. term academic visits programme. £14,186. US Army Pickering, J; Astrophysical Plenio, M; Employing noisy laboratory spectroscopy: improving Dornan, P; PPARC support for EU environments to support quantum the atomic data for astrophysics by Datagrid. £421,748. information processing. £56,290. high resolution Fourier transform spectroscopy. £110,996. Sumner, T; Technology devel- US Department of Energy opment for gravitational wave space Chittenden, J; Centre for the study Dainty, J C; Compact wavefront missions- internal sensor charge of pulsed power driven high energy sensing for the assessment of the control. £81,041. density plasmas. £225,807. refractive state of the eye. £153,951. Royal Society Wellcome Trust Beige, A; Royal Society Fellowship. French, P; Wellcome Trust Dainty, J C and Paterson, C; High £220,176. showcase award. £125,000. angular resolution imaging. £165,452. Pendry, J; String theory, quantum field theory, quantum gravity. Cargill, P; Studies of solar and £55,000. space plasmas Fellowship: Prof Cargill. £108,994. Sandia National Laboratories Chittenden, J and Lebedev, S; Meikle, W P; The origin, explosion Experimental and computational and fate of core-collapse super- studies of wire arrays. £85,000. novae. £167,233.

45 Collaborations

Physics is an international science, Institute for High Energy Physics, Stockholm Observatory, Sweden and many aspects of our research Russia Technical University of involve collaborations with colleagues Institute for Space Research, Austria Braunschweig, Germany at institutions in the UK and throughout Institute for Nuclear Physics, Bulgaria Technical University of Denmark, the world. These include: Lyngby, Denmark Institute of Chemical Physics, Spain Technical University of Vienna, Austria Air Products and Chemicals Inc., USA Institute of Nuclear Research, Russia Technion, Israel Anglo Australian Observatory, Australia International Space Science Institute, Switzerland THALES Paris, France Arhus University, Denmark Isaac Newton Group, La Palma, Spain The AtlantIC Alliance Astrophysics Research Institute Jet Propulsion Laboratory, USA The Dow Chemical Company, USA British Petroleum International, UK Kentech Instruments Ltd Trieste Observatory, Italy California Institute of Technology, USA KFKI, Budapest, Hungary UK Meteorological Office Centre dÕEtudes des Rayonnements Spatiaux (CERS), France Kings College London UMIST CERN Los Alamos National Laboratory, USA Universidad Aut—noma de Madrid, Spain CNR-IFAC, Firenze, Italy Lucent Laboratories Universidad de Zaragoza, Spain Complutense University, Madrid Massachusetts Institute of Technology, USA UniversitŽ Louis Pasteur, Cornell University, USA Strasbourg, France Matsushita Electric Works, Japan Delft University of Technology, The Netherlands Max Planck Institute, Garching, University College London Germany Donostia International Physics University of Arizona, USA Center (DIPC), San Sebastian, Spain Max Planck Institute, Heidelberg, University of Athens, Greece Germany Ecole Polytechnique Federale University of Austin, USA Lausanne (EPFL), France Max Planck Institute, Kattenburg- Lindeau, Germany University of Bangor Eidgenossische Technische University of Barcelona, Spain Hochschule (ETH), Switzerland MEMC Electronic Materials Inc., USA University of Basilicata, Italy EI Du Pont de Nemours and Merck Ltd, UK Company, USA NASA Langley Research Center, USA University of Birmingham Endoscan Ltd National Institute Standards and University of Bologna, Italy Technology, USA ESA-ESTEC, Holland University of Bonn, Germany National Physical Laboratory European Southern Observatory University of Braunschweig, Germany Free University of Amsterdam, The National Solar Observatory, USA Netherlands NRL Washington, USA University of Bristol Free University Berlin, Germany Observatoire de Nice, France University of Buenos Aires, Brazil Free University of Brussels, Belgium Padua Observatory, Italy University of California Los Angeles, USA Ghent University, Belgium Pennsylvania State University, USA University of California San Diego, GKSS, Germany Perimeter Institute, Waterloo, Canada USA Goddard Space Flight Center, USA Philips Research, The Netherlands University of Cambridge Graz University, Austria Pilsen University, Czech Republic University of Chemnitz, Germany Hadley Climate Research Centre Research Center of Crete, Greece University of Cologne, Germany Harvard Smithsonian Center for Royal Meteorological Institute, University of Colorado, USA Astrophysics, USA Brussels, Belgium University of Hampton, USA Harvard University, USA Rutherford Appleton Laboratory University of Hertfordshire Herriot Watt University Sandia National Laboratory, USA University of Hawaii, USA Hewlett-Packard Laboratories, USA Scottish Environment and Energy Foundation University of Kaiserslautern, Germany High Altitude Observatory, USA Space Telescope Science Institute University of Leeds HRL Laboratories LLC, Malibu, USA Stanford University, USA University of Leicester INAOE, Mexico Steacie Institute for Molecular University of Naples, Italy Sciences, Canada University of Neuchatel, Switzerland 46 University of Newcastle COCOMO, a Research Training QUEST, a European Union IHP University of New South Wales, Network on coherent control of Network collaboration on Quantum Australia atomic processes Optics University of Nottingham Consortium for Computational QGATES, a European Union IST Quantum Many-Body Theory Network collaboration on quantum University of Oslo, Norway COSLAB, an ESF Programme on gates for quantum computing University of Otago, New Zealand Cosmology in the Laboratory QUBITS, an IST Network on University of Oxford D0 Consortium, Fermilab, USA decoherence in atomic logic elements University of Paris XI, Orsay, France ELAIS survey QuICT, a UK EPSRC Network University of Palermo, Italy EPSRC Experimental and Theoretical collaboration on quantum information University of Potsdam, Germany Studies of Electrical Transport in and coherence Organic Electroluminescent Devices University of Reading Programme QUIPROCONE, a European Union University of Rochester, USA IST Network of Excellence coordinating EPSRC Polymer Blend body on quantum information University of Salerno, Italy Semiconductors Programme processing throughout Europe University of Sheffield EPSRC Retinomorphic Imaging QUPRODIS, a Thematic Network on Basic Technology Programme University of Siena, Italy the Quantum Properties of ESF Network on Quantum Information Distributed quantum systems University of Southampton processing Search for supernovae in starburst University of St Andrews ESF-QIT programme on Quantum galaxies University of Strathclyde Information Theory and quantum SOLICE, Solar influences on Climate computation University of Surrey and the Environment European Union training network on University of Sussex Spin Polarised Magnetics Oxides Cold Quantum Gases network and Spintronics Network University of Sydney, Australia FASTNET, a European Union Studies of SN 1987A at very late University of Texas at Austin, USA training network phases University of Valencia, Spain Framework VI, Nanotechnology; SupIRCam, A tool for understanding British Council/DAAD ARC programme University of Wales, Aberystwyth the IR light curves of type Ia FERRUM project: oscillator strengths Supernovae University of Warwick for astrophysics applications The host galaxies of high redshift University of Wurzburg, Germany HERSCHEL SPIRE consortium type Ia supernovae University of York HITRAP, An Ion Trap Facility for The Physics of Type Ia Supernova Washington University, St. Louis, USA Experiments with Highly-Charged Ions Explosions Weizmann Institute, Israel HYTEC, a CEC Framework V IHP The progenitors of massive, core- Network collapse supernovae Wellesley College, USA IR studies of nearby type II supernovae UKCAN, the UK cold atoms network We are members of a significant ISCOM, a EU Network on the UK GridPP Project Information Society as a Complex number of European Union and UKIRT Infrared Deep Sky Survey other collaborative programmes, Network UK Mid-Infrared network including: ISD LINK (DTI/EPSRC) Late-time spectroscopy of type Ia UK National Carbon Based ACQUIRE, a European Union supernovae Electronics Consortium training network London Centre for Nanotechnology AEOLOS, the assessment of the NANOFAB, a European Union impact of SF6 and PFC reservoir training network tracers on global warming PLANCK HFI consortium ALEPH experiment, CERN POE, a European Community RTN ASTRO-F consortium POWERPLAY, a CEC CSG Australian Network of Excellence on programme project Atom Interferometry Ultrafast Photonics Collaboration Basic Technology Attosecond (UPC IRC) Programme Ultrafast spectroscopy of conjugated British Petroleum International (UK) polymers Ð Imperial College Engineering for Sustainable Development Programme SLAM, a programme on Future and Emerging Technologies CMS collaboration SWIRE, the NASA SIRTF Legacy Survey 47 Academic Staff (as of 31st December 2002)

Professors Physics Physics R W Smith, MA, PhD, DIC R J Rivers, PhD Space Physics Physics Laser Physics A Balogh, DIC, MSc D J Southwood, BA, PhD, DIC R A Smith, BSc, PhD Physics Theoretical Physics Physics K W J Barnham, PhD K S Stelle, PhD R C Thompson, MA, PhD Physics Experimental Astrophysics Atmospheric Physics A R Bell, MA, PhD T J Sumner, DPhil R Toumi, PhD, ARCS Experimental Solid State Physics Ultrafast Physics and Technology D Bradley, BSc, PhD, ARCS, FRSA, CPhys Senior Lecturers J R Taylor, BSc, PhD Physics Physics D I Britton, BSc, MSc, PhD P J Cargill, BSc, PhD M J Thompson, BA, MA, PhD R G Burns, PhD Atomic and Molecular Physics K Christensen, PhD Physics J-P Connerade, PhD, ARCS, DIC L F Cohen, BSc, PhD A Tseytlin, MS, PhD Plasma Physics M Coppins, PhD Physics S C Cowley, BA, MA, PhD P G Etchegoin, PhD T S Virdee, PhD Applied Optics R J Forsyth, BSc, PhD Theoretical Solid State Physics J C Dainty, PhD I Liubarsky, BSc, PhD, CPhys, MInstP, D D Vvedensky, PhD FRAS Experimental Particle Physics Physics K Nandra, BA, PhD P J Dornan, BA, PhD D M Websdale, PhD, ARCS M Neil, BA, PhD Physics M B Plenio, Dr. rer. nat Senior Research Fellows J E Drew, BSc, PhD D M Segal, BSc, DPhil Physics T C Bacon, BSc, PhD S J Warren, BA, PhD P M W French, PhD Prof. D M Binnie, PhD K Weir BSc, PhD Atmospheric Physics Prof. D D Burgess, MA, PhD, DIC J Zhang, BSc, ARCS, PhD, DIC J D Haigh, DPhil Prof. I Butterworth, PhD, CBE, FRS Advanced Fellows Physics Prof. A D Caplin, MA, MSc, PhD G Hall, BSc, PhD A E Dangor, BSc D C Brody, BSc, MSc, PhD Earth Observation Prof. M G Haines, PhD, ARCS, FRCO, ARCM A Goussiou, BS, PhD J E Harries, BSc, PhD H F Jones, BA, PhD T S Horbury, BSc, PhD Theoretical Physics Prof. B A Joyce, DSc, FRS A Jaffe, MSc, PhD J J Halliwell, BSc, PhD Prof. T W B Kibble, MA, PhD, FRS R Jesik, BSc, MSc, PhD J Nelson BA, PhD Quantum Optics Prof. E Leader, BSc, MS, PhD C Paterson, BA, PhD E Hinds,BA, DPhil Prof. R Newman, PhD, FRS Prof. J J Quenby, BSc, PhD, DIC, ARCS J C Pickering, BA, MA, PhD, DIC Laser Physics A P Thorne, MA, DPhil S V Popov, MSc, PhD M H R Hutchinson, PhD J W G Tisch, BSc, PhD Theoretical Physics Readers P Torok, DPhil, PhD C J Isham, PhD, ARCS Physics Lecturers Physics M J Damzen, PhD W G Jones, PhD, ARCS High Energy Physics A J Campbell, BSc, MSc, PhD Quantum Optics P D Dauncey, BA, DPhil G Davies, BSc, PhD U Egede, BSc, PhD P L Knight, DPhil, FRS Space Physics T S Evans, BA, PhD Theoretical Solid State Physics M K Dougherty, BSc, PhD A Mackinnon, PhD C N Guy, PhD High Energy Physics D K K Lee, BA, PhD Laser Physics C Foudas, MA, M.Phil, PhD V Moore, PhD J Marangos, PhD Physics Z Najmudin, BA, PhD Physics W M C Foulkes, PhD B Sauer, BA, PhD W P S Meikle, PhD, FRAS Physics Y C Unruh, MSc, PhD Nonlinear Optics J F Hassard, PhD V Vedral, BSc, PhD G H C New, DPhil Plasma Physics Visiting Professors Applied Physics K M Krushelnick BSc, MA, PhD G Parry, BSc, PhD, DIC Physics M E Barnett, BSc, BA, PhD Theoretical Solid State Physics K R Long, BSc, DPhil J Gallop, BA, DPhil J B Pendry, MA, PhD, FRS Theoretical Physics P Gill, BSc, DPhil Experimental Solid State Physics J C R Magueijo, BA, PhD I Grant, FRS R Hastie, BSc, MSc C C Phillips, PhD Photonics Physics L B Lucy, BSc, PhD Astrophysics M W McCall, PhD M J Rowan-Robinson, PhD Sir Martin J Rees, MA, PhD FRS Physics J C Thompson, MA, PhD J Nash, PhD

48 Contacts

Astrophysics Group Page 4 Head of Group: Professor M Rowan-Robinson Tel: 020 7594 7530, Fax: 020 7594 7777, e-mail: [email protected]

Condensed Matter Theory Group Page 7 Head of Group: Professor D D Vvedensky Tel: 020 7594 7605, Fax: 020 7594 7604, e-mail: [email protected]

Experimental Solid State Physics Group and Centre for Electronic Materials and Devices Page 10 Head of Group: Professor D C C Bradley Tel: 020 7594 6693, Fax : 020 7594 7580, e-mail: [email protected]

High Energy Physics Group Page 16 Head of Group: Professor P J Dornan Tel: 020 7594 7822, Fax: 020 7823 8830, e-mail: [email protected]

The Laser Consortium Page 19 Director: Professor J P Marangos Tel: 020 7594 7727, Fax: 020 7823 8376, e-mail: [email protected]

Photonics Page 22 Head of Group: Professor P M W French Tel: 020 7594 7712, Fax: 020 7594 7714, e-mail: [email protected]

Plasma Physics Group Page 25 Head of Group: Professor S C Cowley Tel: 020 7594 7656, Fax: 020 7594 7658, e-mail: [email protected]

Quantum Optics and Laser Science Page 28 Head of Group: Professor G H C New Tel: 020 7594 7727, Fax: 020 7823 8376, e-mail: [email protected]

Space and Atmospheric Physics Group Page 31 Head of Group: Professor J E Harries Tel: 020 7594 7670, Fax: 020 7594 7772, e-mail: [email protected]

Theoretical Physics Group Page 34 Head of Group: Professor K Stelle Tel: 020 7594 7841, Fax: 020 7594 7844, e-mail: [email protected]