The Photon Wave Function in Principle and in Practice Vincent Debierre
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Relativistic Dynamics
Chapter 4 Relativistic dynamics We have seen in the previous lectures that our relativity postulates suggest that the most efficient (lazy but smart) approach to relativistic physics is in terms of 4-vectors, and that velocities never exceed c in magnitude. In this chapter we will see how this 4-vector approach works for dynamics, i.e., for the interplay between motion and forces. A particle subject to forces will undergo non-inertial motion. According to Newton, there is a simple (3-vector) relation between force and acceleration, f~ = m~a; (4.0.1) where acceleration is the second time derivative of position, d~v d2~x ~a = = : (4.0.2) dt dt2 There is just one problem with these relations | they are wrong! Newtonian dynamics is a good approximation when velocities are very small compared to c, but outside of this regime the relation (4.0.1) is simply incorrect. In particular, these relations are inconsistent with our relativity postu- lates. To see this, it is sufficient to note that Newton's equations (4.0.1) and (4.0.2) predict that a particle subject to a constant force (and initially at rest) will acquire a velocity which can become arbitrarily large, Z t ~ d~v 0 f ~v(t) = 0 dt = t ! 1 as t ! 1 . (4.0.3) 0 dt m This flatly contradicts the prediction of special relativity (and causality) that no signal can propagate faster than c. Our task is to understand how to formulate the dynamics of non-inertial particles in a manner which is consistent with our relativity postulates (and then verify that it matches observation, including in the non-relativistic regime). -
Introductory Lectures on Quantum Field Theory
Introductory Lectures on Quantum Field Theory a b L. Álvarez-Gaumé ∗ and M.A. Vázquez-Mozo † a CERN, Geneva, Switzerland b Universidad de Salamanca, Salamanca, Spain Abstract In these lectures we present a few topics in quantum field theory in detail. Some of them are conceptual and some more practical. They have been se- lected because they appear frequently in current applications to particle physics and string theory. 1 Introduction These notes are based on lectures delivered by L.A.-G. at the 3rd CERN–Latin-American School of High- Energy Physics, Malargüe, Argentina, 27 February–12 March 2005, at the 5th CERN–Latin-American School of High-Energy Physics, Medellín, Colombia, 15–28 March 2009, and at the 6th CERN–Latin- American School of High-Energy Physics, Natal, Brazil, 23 March–5 April 2011. The audience on all three occasions was composed to a large extent of students in experimental high-energy physics with an important minority of theorists. In nearly ten hours it is quite difficult to give a reasonable introduction to a subject as vast as quantum field theory. For this reason the lectures were intended to provide a review of those parts of the subject to be used later by other lecturers. Although a cursory acquaintance with the subject of quantum field theory is helpful, the only requirement to follow the lectures is a working knowledge of quantum mechanics and special relativity. The guiding principle in choosing the topics presented (apart from serving as introductions to later courses) was to present some basic aspects of the theory that present conceptual subtleties. -
Appendix D: the Wave Vector
General Appendix D-1 2/13/2016 Appendix D: The Wave Vector In this appendix we briefly address the concept of the wave vector and its relationship to traveling waves in 2- and 3-dimensional space, but first let us start with a review of 1- dimensional traveling waves. 1-dimensional traveling wave review A real-valued, scalar, uniform, harmonic wave with angular frequency and wavelength λ traveling through a lossless, 1-dimensional medium may be represented by the real part of 1 ω the complex function ψ (xt , ): ψψ(x , t )= (0,0) exp(ikx− i ω t ) (D-1) where the complex phasor ψ (0,0) determines the wave’s overall amplitude as well as its phase φ0 at the origin (xt , )= (0,0). The harmonic function’s wave number k is determined by the wavelength λ: k = ± 2πλ (D-2) The sign of k determines the wave’s direction of propagation: k > 0 for a wave traveling to the right (increasing x). The wave’s instantaneous phase φ(,)xt at any position and time is φφ(,)x t=+−0 ( kx ω t ) (D-3) The wave number k is thus the spatial analog of angular frequency : with units of radians/distance, it equals the rate of change of the wave’s phase with position (with time t ω held constant), i.e. ∂∂φφ k =; ω = − (D-4) ∂∂xt (note the minus sign in the differential expression for ). If a point, originally at (x= xt0 , = 0), moves with the wave at velocity vkφ = ω , then the wave’s phase at that point ω will remain constant: φ(x0+ vtφφ ,) t =++ φ0 kx ( 0 vt ) −=+ ωφ t00 kx The velocity vφ is called the wave’s phase velocity. -
EMT UNIT 1 (Laws of Reflection and Refraction, Total Internal Reflection).Pdf
Electromagnetic Theory II (EMT II); Online Unit 1. REFLECTION AND TRANSMISSION AT OBLIQUE INCIDENCE (Laws of Reflection and Refraction and Total Internal Reflection) (Introduction to Electrodynamics Chap 9) Instructor: Shah Haidar Khan University of Peshawar. Suppose an incident wave makes an angle θI with the normal to the xy-plane at z=0 (in medium 1) as shown in Figure 1. Suppose the wave splits into parts partially reflecting back in medium 1 and partially transmitting into medium 2 making angles θR and θT, respectively, with the normal. Figure 1. To understand the phenomenon at the boundary at z=0, we should apply the appropriate boundary conditions as discussed in the earlier lectures. Let us first write the equations of the waves in terms of electric and magnetic fields depending upon the wave vector κ and the frequency ω. MEDIUM 1: Where EI and BI is the instantaneous magnitudes of the electric and magnetic vector, respectively, of the incident wave. Other symbols have their usual meanings. For the reflected wave, Similarly, MEDIUM 2: Where ET and BT are the electric and magnetic instantaneous vectors of the transmitted part in medium 2. BOUNDARY CONDITIONS (at z=0) As the free charge on the surface is zero, the perpendicular component of the displacement vector is continuous across the surface. (DIꓕ + DRꓕ ) (In Medium 1) = DTꓕ (In Medium 2) Where Ds represent the perpendicular components of the displacement vector in both the media. Converting D to E, we get, ε1 EIꓕ + ε1 ERꓕ = ε2 ETꓕ ε1 ꓕ +ε1 ꓕ= ε2 ꓕ Since the equation is valid for all x and y at z=0, and the coefficients of the exponentials are constants, only the exponentials will determine any change that is occurring. -
Electromagnetic Field Theory
Electromagnetic Field Theory BO THIDÉ Υ UPSILON BOOKS ELECTROMAGNETIC FIELD THEORY Electromagnetic Field Theory BO THIDÉ Swedish Institute of Space Physics and Department of Astronomy and Space Physics Uppsala University, Sweden and School of Mathematics and Systems Engineering Växjö University, Sweden Υ UPSILON BOOKS COMMUNA AB UPPSALA SWEDEN · · · Also available ELECTROMAGNETIC FIELD THEORY EXERCISES by Tobia Carozzi, Anders Eriksson, Bengt Lundborg, Bo Thidé and Mattias Waldenvik Freely downloadable from www.plasma.uu.se/CED This book was typeset in LATEX 2" (based on TEX 3.14159 and Web2C 7.4.2) on an HP Visualize 9000⁄360 workstation running HP-UX 11.11. Copyright c 1997, 1998, 1999, 2000, 2001, 2002, 2003 and 2004 by Bo Thidé Uppsala, Sweden All rights reserved. Electromagnetic Field Theory ISBN X-XXX-XXXXX-X Downloaded from http://www.plasma.uu.se/CED/Book Version released 19th June 2004 at 21:47. Preface The current book is an outgrowth of the lecture notes that I prepared for the four-credit course Electrodynamics that was introduced in the Uppsala University curriculum in 1992, to become the five-credit course Classical Electrodynamics in 1997. To some extent, parts of these notes were based on lecture notes prepared, in Swedish, by BENGT LUNDBORG who created, developed and taught the earlier, two-credit course Electromagnetic Radiation at our faculty. Intended primarily as a textbook for physics students at the advanced undergradu- ate or beginning graduate level, it is hoped that the present book may be useful for research workers -
Instantaneous Local Wave Vector Estimation from Multi-Spacecraft Measurements Using Few Spatial Points T
Instantaneous local wave vector estimation from multi-spacecraft measurements using few spatial points T. D. Carozzi, A. M. Buckley, M. P. Gough To cite this version: T. D. Carozzi, A. M. Buckley, M. P. Gough. Instantaneous local wave vector estimation from multi- spacecraft measurements using few spatial points. Annales Geophysicae, European Geosciences Union, 2004, 22 (7), pp.2633-2641. hal-00317540 HAL Id: hal-00317540 https://hal.archives-ouvertes.fr/hal-00317540 Submitted on 14 Jul 2004 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Annales Geophysicae (2004) 22: 2633–2641 SRef-ID: 1432-0576/ag/2004-22-2633 Annales © European Geosciences Union 2004 Geophysicae Instantaneous local wave vector estimation from multi-spacecraft measurements using few spatial points T. D. Carozzi, A. M. Buckley, and M. P. Gough Space Science Centre, University of Sussex, Brighton, England Received: 30 September 2003 – Revised: 14 March 2004 – Accepted: 14 April 2004 – Published: 14 July 2004 Part of Special Issue “Spatio-temporal analysis and multipoint measurements in space” Abstract. We introduce a technique to determine instan- damental assumptions, namely stationarity and homogene- taneous local properties of waves based on discrete-time ity. -
Chapter 2 X-Ray Diffraction and Reciprocal Lattice
Chapter 2 X-ray diffraction and reciprocal lattice I. Waves 1. A plane wave is described as Ψ(x,t) = A ei(k⋅x-ωt) A is the amplitude, k is the wave vector, and ω=2πf is the angular frequency. 2. The wave is traveling along the k direction with a velocity c given by ω=c|k|. Wavelength along the traveling direction is given by |k|=2π/λ. 3. When a wave interacts with the crystal, the plane wave will be scattered by the atoms in a crystal and each atom will act like a point source (Huygens’ principle). 4. This formulation can be applied to any waves, like electromagnetic waves and crystal vibration waves; this also includes particles like electrons, photons, and neutrons. A particular case is X-ray. For this reason, what we learn in X-ray diffraction can be applied in a similar manner to other cases. II. X-ray diffraction in real space – Bragg’s Law 1. A crystal structure has lattice and a basis. X-ray diffraction is a convolution of two: diffraction by the lattice points and diffraction by the basis. We will consider diffraction by the lattice points first. The basis serves as a modification to the fact that the lattice point is not a perfect point source (because of the basis). 2. If each lattice point acts like a coherent point source, each lattice plane will act like a mirror. θ θ θ d d sin θ (hkl) -1- 2. The diffraction is elastic. In other words, the X-rays have the same frequency (hence wavelength and |k|) before and after the reflection. -
(Aka Second Quantization) 1 Quantum Field Theory
221B Lecture Notes Quantum Field Theory (a.k.a. Second Quantization) 1 Quantum Field Theory Why quantum field theory? We know quantum mechanics works perfectly well for many systems we had looked at already. Then why go to a new formalism? The following few sections describe motivation for the quantum field theory, which I introduce as a re-formulation of multi-body quantum mechanics with identical physics content. 1.1 Limitations of Multi-body Schr¨odinger Wave Func- tion We used totally anti-symmetrized Slater determinants for the study of atoms, molecules, nuclei. Already with the number of particles in these systems, say, about 100, the use of multi-body wave function is quite cumbersome. Mention a wave function of an Avogardro number of particles! Not only it is completely impractical to talk about a wave function with 6 × 1023 coordinates for each particle, we even do not know if it is supposed to have 6 × 1023 or 6 × 1023 + 1 coordinates, and the property of the system of our interest shouldn’t be concerned with such a tiny (?) difference. Another limitation of the multi-body wave functions is that it is incapable of describing processes where the number of particles changes. For instance, think about the emission of a photon from the excited state of an atom. The wave function would contain coordinates for the electrons in the atom and the nucleus in the initial state. The final state contains yet another particle, photon in this case. But the Schr¨odinger equation is a differential equation acting on the arguments of the Schr¨odingerwave function, and can never change the number of arguments. -
FFS (UK / USA) «FFS» (Domino Records, Release: 05.06.2015)
FFS (UK / USA) «FFS» (Domino Records, Release: 05.06.2015) Collaborations, as FFS would have us believe on their debut album, don’t work. You start off deferential, and strangely reverential – and eventually, you’ll need the Dalai Lama to mediate, between all the patronising, agonising, navel-gazing and differences in work ethic. So when Los Angeles duo Sparks and Glasgow-based quartet Franz Ferdinand decided to record together, it was a flawed and potentially disastrous idea, right? FFS, you couldn’t be more wrong! Not only is ‘Collaborations Don’t Work’ one of the star attractions of the self- titled record that sprang from their collective loins but ‘FFS’ is also one of the strongest albums of either bands’ career. The love of artful corkscrew pop that created a mutual appreciation society kicks off with the lead single ‘Johnny Delusional’ and its soon-come successor ‘Call Girl’, though the hooks driving ‘Police Encounters’, ‘So Desu Ne’ and ‘Piss Off’ are no less fabulous and merciless. This dynamic thrill is countered by the subtler charms of ‘Dictator’s Son’ and ‘Little Guy From The Suburbs’, the haughtier ‘The Power Couple’ and ‘Collaborations Don’t Work’ itself, a multi-tiered quasi-musical that shows off the compositional ambition and savvy humour that defines ‘FFS’. “The real motivation was to make something new, not ‘Franz featuring Russell Mael’, or ‘Sparks with Franz Ferdinand backing them’,” declares FF frontman Alex Kapranos, whose intertwining lead vocals with Russell is another of the record’s principal thrills, like a male version of the Abba approach. -
Harmonic Oscillator: Motion in a Magnetic Field
Harmonic Oscillator: Motion in a Magnetic Field * The Schrödinger equation in a magnetic field The vector potential * Quantized electron motion in a magnetic field Landau levels * The Shubnikov-de Haas effect Landau-level degeneracy & depopulation The Schrödinger Equation in a Magnetic Field An important example of harmonic motion is provided by electrons that move under the influence of the LORENTZ FORCE generated by an applied MAGNETIC FIELD F ev B (16.1) * From CLASSICAL physics we know that this force causes the electron to undergo CIRCULAR motion in the plane PERPENDICULAR to the direction of the magnetic field * To develop a QUANTUM-MECHANICAL description of this problem we need to know how to include the magnetic field into the Schrödinger equation In this regard we recall that according to FARADAY’S LAW a time- varying magnetic field gives rise to an associated ELECTRIC FIELD B E (16.2) t The Schrödinger Equation in a Magnetic Field To simplify Equation 16.2 we define a VECTOR POTENTIAL A associated with the magnetic field B A (16.3) * With this definition Equation 16.2 reduces to B A E A E (16.4) t t t * Now the EQUATION OF MOTION for the electron can be written as p k A eE e 1k(B) 2k o eA (16.5) t t t 1. MOMENTUM IN THE PRESENCE OF THE MAGNETIC FIELD 2. MOMENTUM PRIOR TO THE APPLICATION OF THE MAGNETIC FIELD The Schrödinger Equation in a Magnetic Field Inspection of Equation 16.5 suggests that in the presence of a magnetic field we REPLACE the momentum operator in the Schrödinger equation -
Basic Four-Momentum Kinematics As
L4:1 Basic four-momentum kinematics Rindler: Ch5: sec. 25-30, 32 Last time we intruduced the contravariant 4-vector HUB, (II.6-)II.7, p142-146 +part of I.9-1.10, 154-162 vector The world is inconsistent! and the covariant 4-vector component as implicit sum over We also introduced the scalar product For a 4-vector square we have thus spacelike timelike lightlike Today we will introduce some useful 4-vectors, but rst we introduce the proper time, which is simply the time percieved in an intertial frame (i.e. time by a clock moving with observer) If the observer is at rest, then only the time component changes but all observers agree on ✁S, therefore we have for an observer at constant speed L4:2 For a general world line, corresponding to an accelerating observer, we have Using this it makes sense to de ne the 4-velocity As transforms as a contravariant 4-vector and as a scalar indeed transforms as a contravariant 4-vector, so the notation makes sense! We also introduce the 4-acceleration Let's calculate the 4-velocity: and the 4-velocity square Multiplying the 4-velocity with the mass we get the 4-momentum Note: In Rindler m is called m and Rindler's I will always mean with . which transforms as, i.e. is, a contravariant 4-vector. Remark: in some (old) literature the factor is referred to as the relativistic mass or relativistic inertial mass. L4:3 The spatial components of the 4-momentum is the relativistic 3-momentum or simply relativistic momentum and the 0-component turns out to give the energy: Remark: Taylor expanding for small v we get: rest energy nonrelativistic kinetic energy for v=0 nonrelativistic momentum For the 4-momentum square we have: As you may expect we have conservation of 4-momentum, i.e. -
MAC BACK on TRACK and Hanging the Exhibitions, Thanks Again
news from 185 bath street AUTUMN 2018 No 46 THE GLASGOW ART CLUB NEWSLETTER President’s Column ince starting my Presidency earlier this year, your Council and I have been working hard Sto make your experience of the Club more fruitful and pleasurable. We now have a dedicated Members’ room where some of you partake of a drink and enjoy the soporific peace of a ticking clock. We have established a comprehensive questionnaire and many of you have responded with interesting proposals. As a result, you can look forward to exciting developments offering you a series of new events, talks and exhibitions. Many thanks to all who have contributed to our fundraising appeal raising approx. £25,000 plus gift aid. This gives us a start to consider President Joe Hargan under the Mackintosh lights in Windyhill, flanked by Paisley Art Institute developing other aspects of the Club for a president David Sutton and Club member Michael McLoughlin. research/archives rooms that can be used for a retreat for our laptop users. For those of you that give of their time and energy being involved in the various committees MAC BACK ON TRACK and hanging the exhibitions, thanks again. If anyone feels that they would like to be more involved in developing the Club by bringing their lans to celebrate the Mackintosh sesquicen- ing (see page 2) They were greeted by Celia Sinclair, professional skills, we would be delighted to hear tenary ran into trouble almost from the start. chair of the Willow Tearooms Trust, whose interest from you. PWhile the Kelvingrove exhibition was voted in the architect was fostered by her involvement in It has been an eventful year so far with our a great success, it was programmed to close just work on 185 Bath Street.