DOCSLIB.ORG

Curriculum Vitae

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Curriculum Vitae Curriculum Vitæ1 ZANARDI, Paolo, Italian and USA Citizenship. Education : 1992{1995 PhD in Physics: Universit`adi Roma \Tor Vergata" Linearization schemes for strongly correlated systems of lattice fermions . Supervisor: Prof. Mario Rasetti (Politecnico of Torino) 1986{1992 M.D. in Physics Universit`adegli Studi di Modena: Dynamical aspects of the atom-surface interaction . Advisor: C. Calandra (Final mark: 110/110 cum laude). Positions occupied: 02/01/13{05/31/13 Visiting Research Professor at the National University of Singa- pore, Centre for Quantum Technologies, Singapore 12/15/11| Full Professor of Physics and Astronomy, University of Southern Califor- nia, Los Angeles (CA) USA 01/01/07{12/15/12 Associate Professor of Physics and Astronomy, University of South- ern California, Los Angeles (CA) USA 07/08/05 {07/09/05 JSPS Visiting Scientist at the Kinki University, Osaka (Japan) 01/11/04 { 30/11/04 Appointment as Visiting Professor at the Perimeter Institute for Theoretical Physics, Waterloo ON (Canada) 01/10/04 { 31/10/04 Appointment as Visiting Scientist (CMI fellow) at the Mas- sachusetts Institute of Technology (MIT), Cambridge MA (USA). 1/03 { 12/03 Appointment as Visiting Scientist (CMI fellow) at the Massachusetts Institute of Technology (MIT), Cambridge MA (USA). [3/03 { 6/03, 10/03{ 12/03] 1/01 { present ISI Foundation, Scientific consultant of the Quantum Information The- ory group Scientific Coordinator of the European FET Project TOPQIP 1Last revision: 10/17/17 02{ 04 High-school professorship in Mathematics [Istituto Tecnico G. Einaudi, Correg- gio (RE)] On leave (\congedo per ragioni di studio e ricerca") up to 2004 when I resigned. 1/97{12/00 ISI Foundation, Torino, Postdoctoral fellowship on Quantum Computation 6/96{12/96 INFM (Sect. G) Pre-postdoctoral fellowship on Statistical mechanics of strongly corelated fermion systems 1/96{5/96 ISI Foundation , Torino, Research fellowship Quantum Computation 10/92{10/95 PhD fellowship at the Universit`adi Roma \Tor Vergata". 5/92{9/92 INFM grant for scientific collaboration at the Universit`adi Modena. Research Topics • Theoretical condensed matter • Quantum Information Processing (QIP) • Decoherence control • Physical Implementation of QIP devices • Geometric and topological QIP • Quantum entanglement in interacting spin systems and systems of indistinguishable particles • Quantum Phase Transitions Teaching Experience: Courses • Course on Dynamical Algebras and strongly correlated fermion systems, Graduate School, Universit`adi Modena (1996) • Course on Introduction to quantum computation and information, Graduate School, Politecnico di Torino (1998) • Course on Quantum information processing, Graduate School, Universit`adel Piemonte Orientale, Alessandria (2000) • Course on Introduction to quantum computation and information Graduate School Universit`adi Perugia (2001) • Course on, Quantum information protection, Scuola nazionale di Fisica della Ma- teria, Villa Gualino, Torino (2002) • Course on Quantum computation and information Graduate School Politecnico di Torino (2005) • I won a high-school professorship in Mathematics in the 2000 National competition (\Concorso" for the Region Emilia Romagna). On leave (\congedo per ragioni di studio e ricerca") up to 2004 when I resigned. • USC, Fall 2007: Advanced Electricity and Magnetism (Phys 508b) • USC, Spring 2008: Fundamentals of Physics II: Electricity and Magnetism (Phys 152L) • USC, Fall 2008, Electricity and Magnetism (Phys 408a) • USC, Spring 2009, Thermodynamics and statistical mechanics, (Phys 316) • USC, Fall 2009, Special Topics in Theoretical Physics (Phys 720) • USC, Spring 2010, 2011 Introduction to Quantum mechanics (Phys 438a) • USC, Fall 2010, Introduction to Quantum mechanics (Phys 438b) • USC, Spring 2011, Introduction to Quantum mechanics (Phys 438a) • USC, Fall 2011, Introduction to Quantum mechanics (Phys 438b) • USC, Spring 2012, Introduction to Quantum mechanics (Phys 438a) • Summer 2012 Universit`adi Modena, Graduate School, Quantum information and the foundation of statistical mechanics, Modena, Italy • USC, Fall 2012, Introduction to Quantum mechanics (Phys 438b) • USC, Fall 2013 Quantum Information and Many-Body Physics (Phys 660) • USC, Spring 2014/15 Quantum mechanics (Phys 558a) • USC, Fall 2014/15/16 Quantum mechanics (Phys 558b) • USC, Spring 2016 Quantum information and many-bosy physics (Phys 660) PhD Students • Georgio Styliaris: start date May 2016{ • • Jeff Marshall: start date May 2014{graduation • • Siddharta Santra (USC): start date Fall 2010. Graduation May 2014 • Damian Abasto (USC): start date spring 2007. Graduation December 2011 • Noah Tobias Jacobson (USC): start date spring 2007. Graduation August 2011 • Paolo Solinas, Universit`adi Genova, PhD Completed in 2002, Thesis Title, Ge- ometric quantum computation and its implementations in semiconductor devices, (Internal advisor: Prof. N. Zangh`ı) • Paolo Giorda, Politecnico di Torino, Thesis Title, Quantum entanglement and con- trol in bosonic systems, PhD completed in 2003 (Internal advisor: Dr. V. Penna) • Alioscia Hamma, Universit`adi Federico II di Napoli, PhD to be completed in 2004, Thesis Title, Topological order and quantum information processing, (Internal advisor: Prof. G. Marmo) Fund Raising Activity Ever since my early PostDoc years I got strongly involved in the Fund Raising activity of the ISI Foundation, at the national as well european level. Since I got at USC (January 2007) I got awarded as Principal Investigator of three NSF grants and I am a co-PI of MURI proposal • I strongly contributed to write down, especially in the Quantum Information as- pects of the of the Advanced Research project (PRA) on Solid state implementation of quantum information processing devices, National Institute of Physics of Matter (INFM). The national coordinator was Prof Mario Rasetti (Politecnico di Torino) and several national nodes were involved. • As above with the project SQID, Semiconductor-based implementation of quantum information processing devices. [1999-2001, IST-1999-11311, Future and Emerging Technologies (FET), 1,6 M EUR ]. This Project was Coordinated for the ISI by Prof. Fausto Rossi (Politecnico di Torino) and gathered nine different european nodes in a research consortium. • I was the European Coordinator of the TOPQIP project (540 K Eur) on Topological quantum information processing [2002-2005, IST-2001-39215, Future and Emerging Technologies (FET), 540 K EUR ]. The consortium comprised other for nodes [MPQ Garching, Imperial College, DAMTP Cambridge, SNS Pisa] • Principal Investigator NSF Award 0803304 (co-PI Prof. D. Lidar): Geometric Quantum Information Processing in Open Systems, $ 150 K, start date 09/01/08, duration 3 years • Principal Investigator NSF Award DMR-0804914 (co-PI Prof. S. Haas): Infor- mation Geometry of Quantum Phase Transitions, $ 390 K, start date 09/01/08, duration 3 years. • Principal Investigator NSF Award 0969969, (co-PI Prof. D. Lidar): Differential Ge- ometric Methods for Quantum Information Processing , 490K, start date 09/01/10, duration 3 years • Co-PI of the MURI Project Control of Quantum Systems: Theory and Experi- ments (PI Daniel Lidar) Grant Number: W911NF-11-1-0268 [teams involved:USC, Iowa State University University of Massachusetts, Boston University of Califor- nia, Riverside Princeton University Griffith University (Australia)] Start date: 09/01/11 -End Date 09/01/16 • Co-PI of the Add-On to the MURI Project Control of Quantum Systems: Theory and Experiments (PI Daniel Lidar) Grant Number: W911NF-11-1-0268, $ 500 K. Start date: 02/01/17 -End Date 07/31/17 Publications 1) P. Zanardi, C. Calandra, Charge and energy exchange between a metal and a two- level particle in a metastable state, Surf. Sci. 290, 141 (1993). 2) M. Rasetti, P. Zanardi, The 2-d extend Hubbard model: a supersymmetric chain- cluster approach, Intl. J. Mod. Phys. B 9, 1375 (1995). 3) A. Danani and P. Zanardi, The auxiliary fermion linearized t-J model, Mod. Phys. Lett. B 9, 1873 (1995). 4) P. Zanardi, Auxiliary Fermion Linearization, J. Phys. A 29, 541 (1996) 5) P. Zanardi, Full diagonalization of the EKS model on small rings, Nuovo Cimento D (1996). 6) P. Zanardi, M. Rasetti, Noiseless Quantum Codes, Phys. Rev. Lett. 79, 3306 (1997) LANL E-print Archive: quant-ph/9705044 7) P. Zanardi, Dissipation and Decoherence in a Quantum Register, Phys. Rev. A 57, 3276 (1998) LANL E-print Archive: quant-ph/9705045 8) P. Zanardi, Dissipative dynamics in a quantum register, Phys. Rev. A 56, 4445 (1997) LANL E-print Archive: quant-ph/9708042 9) P. Zanardi, M. Rasetti, Error Avoiding Quantum Codes, Mod. Phys. Lett. B, 25, 1085 (1997) LANL E-print Archive: quant-ph/9710041 10) P. Zanardi, Quantum Cloning in d dimensions, Phys. Rev. A 58, 3484 (1998) LANL E-print Archive: quant-ph/9804011 11) P. Zanardi, F. Rossi, Quantum Information in Semiconductors: Noiseless Encoding in a Quantum-Dot Array, Phys. Rev. Lett. 81 4572 (1998) LANL E-print Archive: quant-ph/9804016 12) P. Zanardi, F. Rossi, Subdecoherent Information Encoding in a Quantum-Dot Ar- ray, Phys. Rev. B 59 8170 (1999) LANL E-print Archive: quant-ph/9808036 13) P. Zanardi, Symmetrizing Evolutions, Phys. Lett. A 258 (1999) 77 LANL E-print Archive: quant-ph/9809064 14) P. Zanardi, Computation on a Noiseless Quantum Code and Symmetrization, Phys. Rev. A 60 (1999) R729 LANL E-print Archive: quant-ph/9901047 15) M. Rasetti, P. Zanardi, A Possible Strategy to Defeat Decoherence in Quantum Computation: the Role of Symmetries, Dynamical Algebras, and All That Fortschr.
Load more

Recommended publications
  • A Lindblad Model of Quantum Brownian Motion
    A Lindblad model of quantum Brownian motion Aniello Lampo,1, ∗ Soon Hoe Lim,2 Jan Wehr,2 Pietro Massignan,1 and Maciej Lewenstein1, 3 1ICFO { Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain 2Department of Mathematics, University of Arizona, Tucson, AZ 85721-0089, USA 3ICREA { Instituci´oCatalana de Recerca i Estudis Avan¸cats, Lluis Companys 23, E-08010 Barcelona, Spain (Dated: December 16, 2016) The theory of quantum Brownian motion describes the properties of a large class of open quantum systems. Nonetheless, its description in terms of a Born-Markov master equation, widely used in literature, is known to violate the positivity of the density operator at very low temperatures. We study an extension of existing models, leading to an equation in the Lindblad form, which is free of this problem. We study the dynamics of the model, including the detailed properties of its stationary solution, for both constant and position-dependent coupling of the Brownian particle to the bath, focusing in particular on the correlations and the squeezing of the probability distribution induced by the environment. PACS numbers: 05.40.-a,03.65.Yz,72.70.+m,03.75.Gg I. INTRODUCTION default choice for evaluating decoherence and dissipation processes, and in general it provides a way to treat quan- A physical system interacting with the environment is titatively the effects experienced by an open system due referred to as open [1]. In reality, such an interaction to the interaction with the environment [27{30]. Here- is unavoidable, so every physical system is affected by after, we will refer to the central particle studied in the the presence of its surroundings, leading to dissipation, model as the Brownian particle.
    [Show full text]
  • Quantum Dissipation and Decoherence of Collective Telefon 08 21/598-32 34 Prof
    N§ MAI %NRAISONDU -OBILITÏ DÏMÏNAGEMENT E DU3ERVICEDELA RENCONTREDÏTUDIANTS !UPROGRAMMERENCONTREDÏTU TAIRE ÌL5,0!JOUTERÌ COMMUNICATION DIANTSETDENSEIGNANTS CHERCHEURS LACOMPÏTENCEDISCIPLINAIREETLIN ETDENSEIGNANTS LEPROCHAIN CHERCHEURSDANSLE VISITEDUCAMPUS INFORMATIONSSUR GUISTIQUE UNE EXPÏRIENCE BINATIO LES ÏCHANGES %RASMUS3OCRATES NALEETBICULTURELLE TELESTLOBJECTIF BULLETIN DOMAINEDESSCIENCESDE ENTRELES&ACULTÏSDEBIOLOGIEDES DECETTECOLLABORATIONNOVATRICEEN DINFORMATIONS LAVIE5,0 5NIVERSITËT DEUX UNIVERSITÏS PRÏSENTATION DE BIOLOGIEBIOCHIMIE PARAÔTRA DES3AARLANDES PROJETS DE RECHERCHE EN PHARMA LEMAI COLOGIE VIROLOGIE IMMUNOLOGIE ET #ONTACTS 5NE PREMIÒRE RENCONTRE AVAIT EU GÏNÏTIQUEHUMAINEDU:(-" &ACULTÏDESSCIENCESDELAVIE LIEU Ì 3AARBRàCKEN EN MAI $R*OERN0àTZ #ETTERENCONTRE ORGANISÏEÌLINI JPUETZ IBMCU STRASBGFR SUIVIEENFÏVRIERPARLAVENUE TIATIVEDU$R*0àTZETDU#ENTRE #ENTREDELANGUES)," Ì 3TRASBOURG DUN GROUPE DÏTU DELANGUESDEL)NSTITUT,E"ELCÙTÏ #ATHERINE#HOUISSA DIANTS ET DENSEIGNANTS DE LUNI STRASBOURGEOIS DU 0R - 3CHMITT BUREAU( VERSITÏ DE LA 3ARRE ,A E ÏDITION CÙTÏ SARROIS SINSCRIT DANS LE CATHERINECHOUISSA LABLANG ULPU STRASBGFR LE MAI PERMETTRA CETTE CADREDESÏCHANGESENTRELESDEUX FOISAUXSTRASBOURGEOISDEDÏCOU FACULTÏS VISANT Ì LA MISE SUR PIED ;SOMMAIRE VRIR LES LABORATOIRES DU :ENTRUM DUN CURSUS FRANCO ALLEMAND EN FàR(UMANUND-OLEKULARBIOLOGIE 3CIENCES DE LA VIE 5NE ÏTUDIANTE !CTUALITÏS :(-" DEL5NIVERSITÏDELA3ARRE DE L5,0 TERMINE ACTUELLEMENT SA IMPLANTÏS SUR LE SITE DU #(5 DE LICENCE, ÌL5D3 DEUXÏTUDIANTS /RGANISATION 3AARBRàCKEN
    [Show full text]
  • Arxiv:Quant-Ph/0208026V1 5 Aug 2002
    Path Integrals and Their Application to Dissipative Quantum Systems Gert-Ludwig Ingold Institut f¨ur Physik, Universit¨at Augsburg, D-86135 Augsburg arXiv:quant-ph/0208026v1 5 Aug 2002 to be published in “Coherent Evolution in Noisy Environments”, Lecture Notes in Physics, http://link.springer.de/series/lnpp/ c Springer Verlag, Berlin-Heidelberg-New York Path Integrals and Their Application to Dissipative Quantum Systems Gert-Ludwig Ingold Institut f¨ur Physik, Universit¨at Augsburg, D-86135 Augsburg, Germany 1 Introduction The coupling of a system to its environment is a recurrent subject in this collec- tion of lecture notes. The consequences of such a coupling are threefold. First of all, energy may irreversibly be transferred from the system to the environment thereby giving rise to the phenomenon of dissipation. In addition, the fluctuating force exerted by the environment on the system causes fluctuations of the system degree of freedom which manifest itself for example as Brownian motion. While these two effects occur both for classical as well as quantum systems, there exists a third phenomenon which is specific to the quantum world. As a consequence of the entanglement between system and environmental degrees of freedom a coherent superposition of quantum states may be destroyed in a process referred to as decoherence. This effect is of major concern if one wants to implement a quantum computer. Therefore, decoherence is discussed in detail in Chap. 5. Quantum computation, however, is by no means the only topic where the coupling to an environment is relevant. In fact, virtually no real system can be considered as completely isolated from its surroundings.
    [Show full text]
  • Chapter 3 Feynman Path Integral
    Chapter 3 Feynman Path Integral The aim of this chapter is to introduce the concept of the Feynman path integral. As well as developing the general construction scheme, particular emphasis is placed on establishing the interconnections between the quantum mechanical path integral, classical Hamiltonian mechanics and classical statistical mechanics. The practice of path integration is discussed in the context of several pedagogical applications: As well as the canonical examples of a quantum particle in a single and double potential well, we discuss the generalisation of the path integral scheme to tunneling of extended objects (quantum fields), dissipative and thermally assisted quantum tunneling, and the quantum mechanical spin. In this chapter we will temporarily leave the arena of many–body physics and second quantisation and, at least superficially, return to single–particle quantum mechanics. By establishing the path integral approach for ordinary quantum mechanics, we will set the stage for the introduction of functional field integral methods for many–body theories explored in the next chapter. We will see that the path integral not only represents a gateway to higher dimensional functional integral methods but, when viewed from an appropriate perspective, already represents a field theoretical approach in its own right. Exploiting this connection, various techniques and concepts of field theory, viz. stationary phase analyses of functional integrals, the Euclidean formulation of field theory, instanton techniques, and the role of topological concepts in field theory will be motivated and introduced in this chapter. 3.1 The Path Integral: General Formalism Broadly speaking, there are two basic approaches to the formulation of quantum mechan- ics: the ‘operator approach’ based on the canonical quantisation of physical observables Concepts in Theoretical Physics 64 CHAPTER 3.
    [Show full text]
  • Nonequilibrium Fluctuation-Dissipation Inequality and Nonequilibrium
    PHYSICAL REVIEW E 88, 012102 (2013) Nonequilibrium fluctuation-dissipation inequality and nonequilibrium uncertainty principle C. H. Fleming and B. L. Hu Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742, USA Albert Roura Max-Planck-Institut fur¨ Gravitationsphysik (Albert-Einstein-Institut), Am Muhlenberg¨ 1, 14476 Golm, Germany (Received 16 January 2013; revised manuscript received 7 May 2013; published 3 July 2013) The fluctuation-dissipation relation is usually formulated for a system interacting with a heat bath at finite temperature, and often in the context of linear response theory, where only small deviations from the mean are considered. We show that for an open quantum system interacting with a nonequilibrium environment, where temperature is no longer a valid notion, a fluctuation-dissipation inequality exists. Instead of being proportional, quantum fluctuations are bounded below by quantum dissipation, whereas classically the fluctuations vanish at zero temperature. The lower bound of this inequality is exactly satisfied by (zero-temperature) quantum noise and is in accord with the Heisenberg uncertainty principle, in both its microscopic origins and its influence upon systems. Moreover, it is shown that there is a coupling-dependent nonequilibrium fluctuation-dissipation relation that determines the nonequilibrium uncertainty relation of linear systems in the weak-damping limit. DOI: 10.1103/PhysRevE.88.012102 PACS number(s): 05.30.−d, 03.65.Yz, 05.40.−a I. INTRODUCTION instantaneous, but where there is nonlocal damping: The fluctuation-dissipation relation (FDR) is a fundamental t m x¨(t) + 2 dτ γ(t − τ) x˙(τ) − F (x) = ξ(t), (4) relation in nonequilibrium statistical mechanics, dating back to −∞ Einstein’s Nobel Prize-winning work on Brownian motion [1] and Nyquist’s seminal work on electronic conductivity [2].
    [Show full text]
  • Path Integrals with Μ1(X) and Μ2(X) the first and Second Moments of the Transition Probabilities
    1 Introduction to path integrals with ¹1(x) and ¹2(x) the ¯rst and second moments of the transition probabilities. v. January 22, 2006 Another approach is to use path integrals. We will use Phys 719 - M. Hilke the example of a simple brownian motion (the random walk) to illustrate the concept of the path integral (or Wiener integral) in this context. CONTENT ² Classical stochastic dynamics DISCRETE RANDOM WALK ² Brownian motion (random walk) ² Quantum dynamics The discrete random walk describes a particle (or per- son) moving along ¯xed segments for ¯xed time intervals ² Free particle (of unit 1). The choice of direction for each new segment ² Particle in a potential is random. We will assume that only perpendicular di- rection are possible (4 possibilities in 2D and 6 in 3D). ² Driven harmonic oscillator The important quantity is the probability to reach x at 0 0 ² Semiclassical approximation time t, when the random walker started at x at time t : ² Statistical description (imaginary time) P (x; t; x0; t0): (3) ² Quantum dissipative systems For this probability the following normalization condi- tions apply: INTRODUCTION X 0 0 0 0 P (x; t; x ; t) = ±x;x0 and for (t > t ) P (x; t; x ; t ) = 1: Path integrals are used in a variety of ¯elds, including x stochastic dynamics, polymer physics, protein folding, (4) ¯eld theories, quantum mechanics, quantum ¯eld theo- This leads to ries, quantum gravity and string theory. The basic idea 1 X is to sum up all contributing paths. Here we will overview P (x; t + 1; x0; t0) = P (»; t; x0; t0); (5) the technique be starting on classical dynamics, in par- 2D h»i ticular, the random walk problem before we discuss the quantum case by looking at a particle in a potential, and where h»i represent the nearest neighbors of x.
    [Show full text]
  • An Introduction to Quantum Annealing
    An introduction to quantum annealing Diego de Falco and Dario Tamascelli Dipartimento di Scienze dell’Informazione, Universit`adegli Studi di Milano Via Comelico, 39/41, 20135 Milano- Italy e-mail:[email protected],[email protected] Abstract Quantum Annealing, or Quantum Stochastic Optimization, is a classical randomized algorithm which provides good heuristics for the solution of hard optimization problems. The algorithm, suggested by the behaviour of quantum systems, is an example of proficuous cross contamination between classical and quantum computer science. In this survey paper we illustrate how hard combinatorial problems are tackled by quantum computation and present some examples of the heuristics provided by Quantum Annealing. We also present prelimi- nary results about the application of quantum dissipation (as an alter- native to Imaginary Time Evolution) to the task of driving a quantum system toward its state of lowest energy. 1 Introduction Quantum computation stems from a simple observation[23, 19]: any com- putation is ultimately performed on a physical device; to any input-output relation there must correspond a change in the state of the device. If the device is microscopic, then its evolution is ruled by the laws of quantum arXiv:1107.0794v1 [quant-ph] 5 Jul 2011 mechanics. The question of whether the change of evolution rules can lead to a break- through in computational complexity theory is still unanswered [11, 34, 40]. What is known is that a quantum computer would outperform a classi- cal one in specific tasks such as integer factorization [47] and searching an unordered database [28, 29]. In fact, Grover’s algorithm can search a key- word quadratically faster than any classical algorithm, whereas in the case of Shor’s factorization the speedup is exponential.
    [Show full text]
  • Energy-Temperature Uncertainty Relation in Quantum Thermodynamics
    ARTICLE DOI: 10.1038/s41467-018-04536-7 OPEN Energy-temperature uncertainty relation in quantum thermodynamics H.J.D. Miller1 & J. Anders1 It is known that temperature estimates of macroscopic systems in equilibrium are most precise when their energy fluctuations are large. However, for nanoscale systems deviations from standard thermodynamics arise due to their interactions with the environment. Here we 1234567890():,; include such interactions and, using quantum estimation theory, derive a generalised ther- modynamic uncertainty relation valid for classical and quantum systems at all coupling strengths. We show that the non-commutativity between the system’s state and its effective energy operator gives rise to quantum fluctuations that increase the temperature uncertainty. Surprisingly, these additional fluctuations are described by the average Wigner-Yanase- Dyson skew information. We demonstrate that the temperature’s signal-to-noise ratio is constrained by the heat capacity plus a dissipative term arising from the non-negligible interactions. These findings shed light on the interplay between classical and non-classical fluctuations in quantum thermodynamics and will inform the design of optimal nanoscale thermometers. 1 Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK. Correspondence and requests for materials should be addressed to H.J.D.M. (email: [email protected]) or to J.A. (email: [email protected]) NATURE COMMUNICATIONS | (2018) 9:2203 | DOI: 10.1038/s41467-018-04536-7 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/s41467-018-04536-7 ohr suggested that there should exist a form of com- estimate, and we illustrate our bound with an example of a Bplementarity between temperature and energy in thermo- damped harmonic oscillator.
    [Show full text]
  • Chapter 3 Feynman Path Integral
    Chapter 3 Feynman Path Integral The aim of this chapter is to introduce the concept of the Feynman path integral. As well as developing the general construction scheme, particular emphasis is placed on establishing the interconnections between the quantum mechanical path integral, classical Hamiltonian mechanics and classical statistical mechanics. The practice of path integration is discussed in the context of several pedagogical applications: As well as the canonical examples of a quantum particle in a single and double potential well, we discuss the generalisation of the path integral scheme to tunneling of extended objects (quantum fields), dissipative and thermally assisted quantum tunneling, and the quantum mechanical spin. In this chapter we will temporarily leave the arena of many–body physics and second quantisation and, at least superficially, return to single–particle quantum mechanics. By establishing the path integral approach for ordinary quantum mechanics, we will set the stage for the introduction of functional field integral methods for many–body theories explored in the next chapter. We will see that the path integral not only represents a gateway to higher dimensional functional integral methods but, when viewed from an appropriate perspective, already represents a field theoretical approach in its own right. Exploiting this connection, various techniques and concepts of field theory, viz. stationary phase analyses of functional integrals, the Euclidean formulation of field theory, instanton techniques, and the role of topological concepts in field theory will be motivated and introduced in this chapter. 3.1 The Path Integral: General Formalism Broadly speaking, there are two basic approaches to the formulation of quantum mechan- ics: the ‘operator approach’ based on the canonical quantisation of physical observables Concepts in Theoretical Physics 64 CHAPTER3.
    [Show full text]
  • Absence of Spin-Boson Quantum Phase Transition for Transmon Qubits
    Absence of spin-boson quantum phase transition for transmon qubits Kuljeet Kaur,1 Th´eoS´epulcre,2 Nicolas Roch,2 Izak Snyman,3 Serge Florens,2 and Soumya Bera1 1Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076, India 2Univ. Grenoble Alpes, CNRS, Institut N´eel,F-38000 Grenoble, France 3Mandelstam Institute for Theoretical Physics, School of Physics, University of the Witwatersrand, Johannesburg, South Africa Superconducting circuits are currently developed as a versatile platform for the exploration of many-body physics, both at the analog and digital levels. Their building blocks are often idealized as two-level qubits, drawing powerful analogies to quantum spin models. For a charge qubit that is capacitively coupled to a transmission line, this analogy leads to the celebrated spin-boson de- scription of quantum dissipation. We put here into evidence a failure of the two-level paradigm for realistic superconducting devices, due to electrostatic constraints which limit the maximum strength of dissipation. These prevent the occurence of the spin-boson quantum phase transition for trans- mons, even up to relatively large non-linearities. A different picture for the many-body ground state describing strongly dissipative transmons is proposed, showing unusual zero point fluctuations. Quantum computation has been hailed as a promising siderations impose strong constraints on the underlying avenue to tackle a large class of unsolved problems, from models. Third, many-body effects beyond the RWA ap- physics and chemistry [1] to algorithmic complexity [2], proximation are notoriously difficult to simulate due to following an original proposition from Feynman [3], long an exponentially large Hilbert space, for instance in the before the technological and conceptual tools were devel- ultra-strong coupling regime of dissipation [21{23].
    [Show full text]
  • Non-Markovian Open Quantum Dynamics from Dissipative Few-Level Systems to Quantum Thermal Machines Michael Wiedmann 2019
    Non-Markovian Open Quantum Dynamics from Dissipative Few-level Systems to Quantum Thermal Machines kumulative Dissertation zur Erlangung des Doktorgrades Dr. rer. nat. der Fakult¨atf¨ur Naturwissenschaften der Universit¨atUlm vorgelegt von Michael Wiedmann aus Hambach bei Schweinfurt 2019 Amtierender Dekan: Prof. Dr. Thorsten Bernhardt Erstgutachter: Prof. Dr. Joachim Ankerhold Zweitgutachter: Prof. Dr. Matthias Freyberger Tag der Promotion: 20. Dezember 2019 List of publications This cumulative thesis is composed of the following peer-reviewed publications which will be discussed in chronological order: 2016 Time-correlated blip dynamics of open quantum systems, M. Wiedmann, J. T. Stockburger, J. Ankerhold, Phys. Rev. A, 052137 2018 Rectification of heat currents across nonlinear quantum chains: A versatile approach beyond weak thermal contact, T. Motz, M. Wiedmann, J. T. Stockburger, J. Ankerhold, New J. Phys. 20, 113020 2019 Out-of-equilibrium operation of a quantum heat engine: The cost of thermal coupling control, M. Wiedmann, J. T. Stockburger, J. Ankerhold, submitted: https://arxiv.org/abs/1903.11368 v Contents 1 Introduction1 2 Non-Markovian open quantum systems5 2.1 Caldeira-Leggett model and generalized Langevin equation.......6 2.2 Path integral approach and stochastic unraveling............9 2.3 Ohmic reservoirs with frequency cutoff - the SLED........... 15 2.3.1 Time-dependent reservoir coupling................ 16 2.3.2 Adjoint equation of motion..................... 19 2.3.3 System-reservoir correlations in SLED probability space..... 20 2.3.4 SLED with momentum-coupled z(t)-noise............ 25 2.4 Projection operator techniques....................... 27 3 Finite-memory, stochastic reduced state propagation 31 3.1 Spin-boson system............................. 34 3.2 Dissipative three-level system......................
    [Show full text]
  • Random Matrix Approach to Quantum Adiabatic Evolution Algorithms
    Random Matrix Approach to Quantum Adiabatic Evolution Algorithms A. Boulatov∗ and V.N. Smelyanskiyy NASA Ames Research Center, MS 269-3, Moffett Field, CA 94035-1000 (Dated: September 17, 2004) We analyze the power of quantum adiabatic evolution algorithms (QAA) for solv- ing random computationally hard optimization problems within a theoretical frame- work based on the random matrix theory (RMT). We present two types of the driven RMT models. In the first model, the driving Hamiltonian is represented by Brow- nian motion in the matrix space. We use the Brownian motion model to obtain a description of multiple avoided crossing phenomena. We show that the failure mech- anism of the QAA is due to the interaction of the ground state with the "cloud" formed by most of the excited states, confirming that in the driven RMT models, the Landau-Zener scenario of pairwise level repulsions is not relevant for the descrip- tion of non-adiabatic corrections. We show that the QAA has a finite probability of success in a certain range of parameters, implying the polynomial complexity of the algorithm. The second model corresponds to the standard QAA with the problem Hamiltonian taken from the Gaussian Unitary RMT ensemble (GUE). We show that the level dynamics in this model can be mapped onto the dynamics in the Brownian motion model. However, this driven GUE model always leads to the exponential complexity of the algorithm due to the presence of the long-range multiple time correlations of the eigenvalues. Our results indicate that the weakness of effective transitions is the leading effect that can make the Markovian type QAA successful.
    [Show full text]