Huang, Liang; Lai Yingcheng; Ferry, David K.; Goodnick, Stephen M.; Akis, Richard
2009-07-31
The concentrations of wave functions about classical periodic orbits, or quantum scars, are a fundamental phenomenon in physics. An open question is whether scarring can occur in relativistic quantum systems. To address this question, we investigate confinements made of graphene whose classical dynamics are chaotic and find unequivocal evidence of relativistic quantum scars. The scarred states can lead to strong conductance fluctuations in the corresponding open quantum dots via the mechanism of resonant transmission.
Relativistic quantum cryptography
NASA Astrophysics Data System (ADS)
Molotkov, S. N.; Nazin, S. S.
2003-07-01
The problem of unconditional security of quantum cryptography (i.e. the security which is guaranteed by the fundamental laws of nature rather than by technical limitations) is one of the central points in quantum information theory. We propose a relativistic quantum cryptosystem and prove its unconditional security against any eavesdropping attempts. Relativistitic causality arguments allow to demonstrate the security of the system in a simple way. Since the proposed protocol does not empoly collective measurements and quantum codes, the cryptosystem can be experimentally realized with the present state-of-art in fiber optics technologies. The proposed cryptosystem employs only the individual measurements and classical codes and, in addition, the key distribution problem allows to postpone the choice of the state encoding scheme until after the states are already received instead of choosing it before sending the states into the communication channel (i.e. to employ a sort of "antedate" coding).
Relativistic Quantum Communication
NASA Astrophysics Data System (ADS)
Hosler, Dominic
In this Ph.D. thesis, I investigate the communication abilities of non-inertial observers and the precision to which they can measure parametrized states. I introduce relativistic quantum field theory with field quantisation, and the definition and transformations of mode functions in Minkowski, Schwarzschild and Rindler spaces. I introduce information theory by discussing the nature of information, defining the entropic information measures, and highlighting the differences between classical and quantum information. I review the field of relativistic quantum information. We investigate the communication abilities of an inertial observer to a relativistic observer hovering above a Schwarzschild black hole, using the Rindler approximation. We compare both classical communication and quantum entanglement generation of the state merging protocol, for both the single and dual rail encodings. We find that while classical communication remains finite right up to the horizon, the quantum entanglement generation tends to zero. We investigate the observers' abilities to precisely measure the parameter of a state that is communicated between Alice and Rob. This parameter was encoded to either the amplitudes of a single excitation state or the phase of a NOON state. With NOON states the dual rail encoding provided greater precision, which is different to the results for the other situations. The precision was maximum for a particular number of excitations in the NOON state. We calculated the bipartite communication for Alice-Rob and Alice-AntiRob beyond the single mode approximation. Rob and AntiRob are causally disconnected counter-accelerating observers. We found that Alice must choose in advance with whom, Rob or AntiRob she wants to create entanglement using a particular setup. She could communicate classically to both.
Consistent resolution of some relativistic quantum paradoxes
Griffiths, Robert B.
2002-12-01
A relativistic version of the (consistent or decoherent) histories approach to quantum theory is developed on the basis of earlier work by Hartle, and used to discuss relativistic forms of the paradoxes of spherical wave packet collapse, Bohm's formulation of the Einstein-Podolsky-Rosen paradox, and Hardy's paradox. It is argued that wave function collapse is not needed for introducing probabilities into relativistic quantum mechanics, and in any case should never be thought of as a physical process. Alternative approaches to stochastic time dependence can be used to construct a physical picture of the measurement process that is less misleading than collapse models. In particular, one can employ a coarse-grained but fully quantum-mechanical description in which particles move along trajectories, with behavior under Lorentz transformations the same as in classical relativistic physics, and detectors are triggered by particles reaching them along such trajectories. States entangled between spacelike separate regions are also legitimate quantum descriptions, and can be consistently handled by the formalism presented here. The paradoxes in question arise because of using modes of reasoning which, while correct for classical physics, are inconsistent with the mathematical structure of quantum theory, and are resolved (or tamed) by using a proper quantum analysis. In particular, there is no need to invoke, nor any evidence for, mysterious long-range superluminal influences, and thus no incompatibility, at least from this source, between relativity theory and quantum mechanics.
Relativistic quantum cryptography
Molotkov, S. N.
2011-03-15
A new protocol of quantum key distribution is proposed to transmit keys through free space. Along with quantum-mechanical restrictions on the discernibility of nonorthogonal quantum states, the protocol uses additional restrictions imposed by special relativity theory. Unlike all existing quantum key distribution protocols, this protocol ensures key secrecy for a not strictly one-photon source of quantum states and an arbitrary length of a quantum communication channel.
BOOK REVIEW: Relativistic Quantum Mechanics
NASA Astrophysics Data System (ADS)
Antoine, J.-P.
2004-01-01
The aim of relativistic quantum mechanics is to describe the finer details of the structure of atoms and molecules, where relativistic effects become nonnegligible. It is a sort of intermediate realm, between the familiar nonrelativistic quantum mechanics and fully relativistic quantum field theory, and thus it lacks the simplicity and elegance of both. Yet it is a necessary tool, mostly for quantum chemists. Pilkuhn's book offers to this audience an up-to-date survey of these methods, which is quite welcome since most previous textbooks are at least ten years old. The point of view of the author is to start immediately in the relativistic domain, following the lead of Maxwell's equations rather than classical mechanics, and thus to treat the nonrelativistic version as an approximation. Thus Chapter 1 takes off from Maxwell's equations (in the noncovariant Coulomb gauge) and gradually derives the basic aspects of Quantum Mechanics in a rather pedestrian way (states and observables, Hilbert space, operators, quantum measurement, scattering,. Chapter 2 starts with the Lorentz transformations, then continues with the Pauli spin equation and the Dirac equation and some of their applications (notably the hydrogen atom). Chapter 3 is entitled `Quantum fields and particles', but falls short of treating quantum field theory properly: only creation/annihilation operators are considered, for a particle in a box. The emphasis is on two-electron states (the Pauli principle, the Foldy--Wouthuysen elimination of small components of Dirac spinors, Breit projection operators. Chapter 4 is devoted to scattering theory and the description of relativistic bound states. Chapter 5, finally, covers hyperfine interactions and radiative corrections. As we said above, relativistic quantum mechanics is by nature limited in scope and rather inelegant and Pilkuhn's book is no exception. The notation is often heavy (mostly noncovariant) and the mathematical level rather low. The central topic
Localization and Entanglement in Relativistic Quantum Physics
NASA Astrophysics Data System (ADS)
Yngvason, Jakob
These notes are a slightly expanded version of a lecture presented in February 2012 at the workshop "The Message of Quantum Science—Attempts Towards a Synthesis" held at the ZIF in Bielefeld. The participants were physicists with a wide range of different expertise and interests. The lecture was intended as a survey of a small selection of the insights into the structure of relativistic quantum physics that have accumulated through the efforts of many people over more than 50 years. (Including, among many others, R. Haag, H. Araki, D. Kastler, H.-J. Borchers, A. Wightman, R. Streater, B. Schroer, H. Reeh, S. Schlieder, S. Doplicher, J. Roberts, R. Jost, K. Hepp, J. Fröhlich, J. Glimm, A. Jaffe, J. Bisognano, E. Wichmann, D. Buchholz, K. Fredenhagen, R. Longo, D. Guido, R. Brunetti, J. Mund, S. Summers, R. Werner, H. Narnhofer, R. Verch, G. Lechner, ….) This contribution discusses some facts about relativistic quantum physics, most of which are quite familiar to practitioners of Algebraic Quantum Field Theory (AQFT) [Also known as Local Quantum Physics (Haag, Local quantum physics. Springer, Berlin, 1992).] but less well known outside this community. No claim of originality is made; the goal of this contribution is merely to present these facts in a simple and concise manner, focusing on the following issues: Explaining how quantum mechanics (QM) combined with (special) relativity, in particular an upper bound on the propagation velocity of effects, leads naturally to systems with an infinite number of degrees of freedom (relativistic quantum fields).
Relativistic quantum private database queries
NASA Astrophysics Data System (ADS)
Sun, Si-Jia; Yang, Yu-Guang; Zhang, Ming-Ou
2015-04-01
Recently, Jakobi et al. (Phys Rev A 83, 022301, 2011) suggested the first practical private database query protocol (J-protocol) based on the Scarani et al. (Phys Rev Lett 92, 057901, 2004) quantum key distribution protocol. Unfortunately, the J-protocol is just a cheat-sensitive private database query protocol. In this paper, we present an idealized relativistic quantum private database query protocol based on Minkowski causality and the properties of quantum information. Also, we prove that the protocol is secure in terms of the user security and the database security.
Quantum probability assignment limited by relativistic causality.
Han, Yeong Deok; Choi, Taeseung
2016-01-01
Quantum theory has nonlocal correlations, which bothered Einstein, but found to satisfy relativistic causality. Correlation for a shared quantum state manifests itself, in the standard quantum framework, by joint probability distributions that can be obtained by applying state reduction and probability assignment that is called Born rule. Quantum correlations, which show nonlocality when the shared state has an entanglement, can be changed if we apply different probability assignment rule. As a result, the amount of nonlocality in quantum correlation will be changed. The issue is whether the change of the rule of quantum probability assignment breaks relativistic causality. We have shown that Born rule on quantum measurement is derived by requiring relativistic causality condition. This shows how the relativistic causality limits the upper bound of quantum nonlocality through quantum probability assignment. PMID:26971717
Quantum probability assignment limited by relativistic causality
Han, Yeong Deok; Choi, Taeseung
2016-01-01
Quantum theory has nonlocal correlations, which bothered Einstein, but found to satisfy relativistic causality. Correlation for a shared quantum state manifests itself, in the standard quantum framework, by joint probability distributions that can be obtained by applying state reduction and probability assignment that is called Born rule. Quantum correlations, which show nonlocality when the shared state has an entanglement, can be changed if we apply different probability assignment rule. As a result, the amount of nonlocality in quantum correlation will be changed. The issue is whether the change of the rule of quantum probability assignment breaks relativistic causality. We have shown that Born rule on quantum measurement is derived by requiring relativistic causality condition. This shows how the relativistic causality limits the upper bound of quantum nonlocality through quantum probability assignment. PMID:26971717
Point form relativistic quantum mechanics and relativistic SU(6)
NASA Technical Reports Server (NTRS)
Klink, W. H.
1993-01-01
The point form is used as a framework for formulating a relativistic quantum mechanics, with the mass operator carrying the interactions of underlying constituents. A symplectic Lie algebra of mass operators is introduced from which a relativistic harmonic oscillator mass operator is formed. Mass splittings within the degenerate harmonic oscillator levels arise from relativistically invariant spin-spin, spin-orbit, and tensor mass operators. Internal flavor (and color) symmetries are introduced which make it possible to formulate a relativistic SU(6) model of baryons (and mesons). Careful attention is paid to the permutation symmetry properties of the hadronic wave functions, which are written as polynomials in Bargmann spaces.
Lattice Boltzmann equation for relativistic quantum mechanics.
Succi, Sauro
2002-03-15
Relativistic versions of the quantum lattice Boltzmann equation are discussed. It is shown that the inclusion of nonlinear interactions requires the standard collision operator to be replaced by a pair of dynamic fields coupling to the relativistic wave function in a way which can be described by a multicomponent complex lattice Boltzmann equation. PMID:16210189
Relativistic quantum corrections to laser wakefield acceleration.
Zhu, Jun; Ji, Peiyong
2010-03-01
The influence of quantum effects on the interaction of intense laser fields with plasmas is investigated by using a hydrodynamic model based on the framework of the relativistic quantum theory. Starting from the covariant Wigner function and Dirac equation, the hydrodynamic equations for relativistic quantum plasmas are derived. Based on the relativistic quantum hydrodynamic equations and Poisson equation, the perturbations of electron number densities and the electric field of the laser wakefield containing quantum effects are deduced. It is found that the corrections generated by the quantum effects to the perturbations of electron number densities and the accelerating field of the laser wakefield cannot be neglected. Quantum effects will suppress laser wakefields, which is a classical manifestation of quantum decoherence effects, however, the contribution of quantum effects for the laser wakefield correction will been partially counteracted by the relativistic effects. The analysis also reveals that quantum effects enlarge the effective frequencies of plasmas, and the quantum behavior appears a screening effect for plasma electrons. PMID:20365881
Relativistic quantum corrections to laser wakefield acceleration
Zhu Jun; Ji Peiyong
2010-03-15
The influence of quantum effects on the interaction of intense laser fields with plasmas is investigated by using a hydrodynamic model based on the framework of the relativistic quantum theory. Starting from the covariant Wigner function and Dirac equation, the hydrodynamic equations for relativistic quantum plasmas are derived. Based on the relativistic quantum hydrodynamic equations and Poisson equation, the perturbations of electron number densities and the electric field of the laser wakefield containing quantum effects are deduced. It is found that the corrections generated by the quantum effects to the perturbations of electron number densities and the accelerating field of the laser wakefield cannot be neglected. Quantum effects will suppress laser wakefields, which is a classical manifestation of quantum decoherence effects, however, the contribution of quantum effects for the laser wakefield correction will been partially counteracted by the relativistic effects. The analysis also reveals that quantum effects enlarge the effective frequencies of plasmas, and the quantum behavior appears a screening effect for plasma electrons.
Relativistic Quantum Mechanics and Field Theory
NASA Astrophysics Data System (ADS)
Gross, Franz
1999-04-01
An accessible, comprehensive reference to modern quantum mechanics and field theory. In surveying available books on advanced quantum mechanics and field theory, Franz Gross determined that while established books were outdated, newer titles tended to focus on recent developments and disregard the basics. Relativistic Quantum Mechanics and Field Theory fills this striking gap in the field. With a strong emphasis on applications to practical problems as well as calculations, Dr. Gross provides complete, up-to-date coverage of both elementary and advanced topics essential for a well-rounded understanding of the field. Developing the material at a level accessible even to newcomers to quantum mechanics, the book begins with topics that every physicist should know-quantization of the electromagnetic field, relativistic one body wave equations, and the theoretical explanation of atomic decay. Subsequent chapters prepare readers for advanced work, covering such major topics as gauge theories, path integral techniques, spontaneous symmetry breaking, and an introduction to QCD, chiral symmetry, and the Standard Model. A special chapter is devoted to relativistic bound state wave equations-an important topic that is often overlooked in other books. Clear and concise throughout, Relativistic Quantum Mechanics and Field Theory boasts examples from atomic and nuclear physics as well as particle physics, and includes appendices with background material. It is an essential reference for anyone working in quantum mechanics today.
Relativistic Quantum Metrology: Exploiting relativity to improve quantum measurement technologies
Ahmadi, Mehdi; Bruschi, David Edward; Sabín, Carlos; Adesso, Gerardo; Fuentes, Ivette
2014-01-01
We present a framework for relativistic quantum metrology that is useful for both Earth-based and space-based technologies. Quantum metrology has been so far successfully applied to design precision instruments such as clocks and sensors which outperform classical devices by exploiting quantum properties. There are advanced plans to implement these and other quantum technologies in space, for instance Space-QUEST and Space Optical Clock projects intend to implement quantum communications and quantum clocks at regimes where relativity starts to kick in. However, typical setups do not take into account the effects of relativity on quantum properties. To include and exploit these effects, we introduce techniques for the application of metrology to quantum field theory. Quantum field theory properly incorporates quantum theory and relativity, in particular, at regimes where space-based experiments take place. This framework allows for high precision estimation of parameters that appear in quantum field theory including proper times and accelerations. Indeed, the techniques can be applied to develop a novel generation of relativistic quantum technologies for gravimeters, clocks and sensors. As an example, we present a high precision device which in principle improves the state-of-the-art in quantum accelerometers by exploiting relativistic effects. PMID:24851858
Relativistic Quantum Metrology: Exploiting relativity to improve quantum measurement technologies
NASA Astrophysics Data System (ADS)
Ahmadi, Mehdi; Bruschi, David Edward; Sabín, Carlos; Adesso, Gerardo; Fuentes, Ivette
2014-05-01
We present a framework for relativistic quantum metrology that is useful for both Earth-based and space-based technologies. Quantum metrology has been so far successfully applied to design precision instruments such as clocks and sensors which outperform classical devices by exploiting quantum properties. There are advanced plans to implement these and other quantum technologies in space, for instance Space-QUEST and Space Optical Clock projects intend to implement quantum communications and quantum clocks at regimes where relativity starts to kick in. However, typical setups do not take into account the effects of relativity on quantum properties. To include and exploit these effects, we introduce techniques for the application of metrology to quantum field theory. Quantum field theory properly incorporates quantum theory and relativity, in particular, at regimes where space-based experiments take place. This framework allows for high precision estimation of parameters that appear in quantum field theory including proper times and accelerations. Indeed, the techniques can be applied to develop a novel generation of relativistic quantum technologies for gravimeters, clocks and sensors. As an example, we present a high precision device which in principle improves the state-of-the-art in quantum accelerometers by exploiting relativistic effects.
Relativistic quantum metrology: exploiting relativity to improve quantum measurement technologies.
Ahmadi, Mehdi; Bruschi, David Edward; Sabín, Carlos; Adesso, Gerardo; Fuentes, Ivette
2014-01-01
We present a framework for relativistic quantum metrology that is useful for both Earth-based and space-based technologies. Quantum metrology has been so far successfully applied to design precision instruments such as clocks and sensors which outperform classical devices by exploiting quantum properties. There are advanced plans to implement these and other quantum technologies in space, for instance Space-QUEST and Space Optical Clock projects intend to implement quantum communications and quantum clocks at regimes where relativity starts to kick in. However, typical setups do not take into account the effects of relativity on quantum properties. To include and exploit these effects, we introduce techniques for the application of metrology to quantum field theory. Quantum field theory properly incorporates quantum theory and relativity, in particular, at regimes where space-based experiments take place. This framework allows for high precision estimation of parameters that appear in quantum field theory including proper times and accelerations. Indeed, the techniques can be applied to develop a novel generation of relativistic quantum technologies for gravimeters, clocks and sensors. As an example, we present a high precision device which in principle improves the state-of-the-art in quantum accelerometers by exploiting relativistic effects. PMID:24851858
Towards universal quantum computation through relativistic motion
Bruschi, David Edward; Sabín, Carlos; Kok, Pieter; Johansson, Göran; Delsing, Per; Fuentes, Ivette
2016-01-01
We show how to use relativistic motion to generate continuous variable Gaussian cluster states within cavity modes. Our results can be demonstrated experimentally using superconducting circuits where tuneable boundary conditions correspond to mirrors moving with velocities close to the speed of light. In particular, we propose the generation of a quadripartite square cluster state as a first example that can be readily implemented in the laboratory. Since cluster states are universal resources for universal one-way quantum computation, our results pave the way for relativistic quantum computation schemes. PMID:26860584
A Quantum Relativistic Prisoner's Dilemma Cellular Automaton
NASA Astrophysics Data System (ADS)
Alonso-Sanz, Ramón; Carvalho, Márcio; Situ, Haozhen
2016-06-01
The effect of variable entangling on the dynamics of a spatial quantum relativistic formulation of the iterated prisoner's dilemma game is studied in this work. The game is played in the cellular automata manner, i.e., with local and synchronous interaction. The game is assessed in fair and unfair contests.
Optimization of a relativistic quantum mechanical engine
NASA Astrophysics Data System (ADS)
Peña, Francisco J.; Ferré, Michel; Orellana, P. A.; Rojas, René G.; Vargas, P.
2016-08-01
We present an optimal analysis for a quantum mechanical engine working between two energy baths within the framework of relativistic quantum mechanics, adopting a first-order correction. This quantum mechanical engine, with the direct energy leakage between the energy baths, consists of two adiabatic and two isoenergetic processes and uses a three-level system of two noninteracting fermions as its working substance. Assuming that the potential wall moves at a finite speed, we derive the expression of power output and, in particular, reproduce the expression for the efficiency at maximum power.
Quantum simulations of relativistic quantum physics in circuit QED
NASA Astrophysics Data System (ADS)
Pedernales, J. S.; Di Candia, R.; Ballester, D.; Solano, E.
2013-05-01
We present a scheme for simulating relativistic quantum physics in circuit quantum electrodynamics. By using three classical microwave drives, we show that a superconducting qubit strongly coupled to a resonator field mode can be used to simulate the dynamics of the Dirac equation and Klein paradox in all regimes. Using the same setup we also propose the implementation of the Foldy-Wouthuysen canonical transformation, after which the time derivative of the position operator becomes a constant of the motion.
NASA Astrophysics Data System (ADS)
Bodek, K.; Caban, P.; Ciborowski, J.; Enders, J.; Köhler, A.; Kozela, A.; Rembieliński, J.; Rozpedzik, D.; Włodarczyk, M.; Zejma, J.
2013-11-01
The Polish-German project QUEST aims at studying relativistic quantum spin correlations of the Einstein-Rosen-Podolsky-Bohm type, through measurement of the correlation function and the corresponding probabilities for relativistic electron pairs. The results will be compared to theoretical predictions obtained by us within the framework of relativistic quantum mechanics, based on assumptions regarding the form of the relativistic spin operator. Agreement or divergence will be interpreted in the context of non-uniqueness of the relativistic spin operator in quantum mechanics as well as dependence of the correlation function on the choice of observables representing the spin. Pairs of correlated electrons will originate from the Mo/ller scattering of polarized 15 MeV electrons provided by the superconducting Darmstadt electron linear accelerator S-DALINAC, TU Darmstadt, incident on a Be target. Spin projections will be determined using the Mott polarimetry technique. Measurements (starting 2013) are planned for longitudinal and transverse beam polarizations and different orientations of the beam polarization vector w.r.t. the Mo/ller scattering plane. This is the first project to study relativistic spin correlations for particles with mass.
Bodek, K.; Rozpędzik, D.; Zejma, J.; Caban, P.; Rembieliński, J.; Włodarczyk, M.; Enders, J.; Köhler, A.; Kozela, A.
2013-11-07
The Polish-German project QUEST aims at studying relativistic quantum spin correlations of the Einstein-Rosen-Podolsky-Bohm type, through measurement of the correlation function and the corresponding probabilities for relativistic electron pairs. The results will be compared to theoretical predictions obtained by us within the framework of relativistic quantum mechanics, based on assumptions regarding the form of the relativistic spin operator. Agreement or divergence will be interpreted in the context of non-uniqueness of the relativistic spin operator in quantum mechanics as well as dependence of the correlation function on the choice of observables representing the spin. Pairs of correlated electrons will originate from the Mo/ller scattering of polarized 15 MeV electrons provided by the superconducting Darmstadt electron linear accelerator S-DALINAC, TU Darmstadt, incident on a Be target. Spin projections will be determined using the Mott polarimetry technique. Measurements (starting 2013) are planned for longitudinal and transverse beam polarizations and different orientations of the beam polarization vector w.r.t. the Mo/ller scattering plane. This is the first project to study relativistic spin correlations for particles with mass.
Deterministic relativistic quantum bit commitment
NASA Astrophysics Data System (ADS)
Adlam, Emily; Kent, Adrian
2015-06-01
We describe new unconditionally secure bit commitment schemes whose security is based on Minkowski causality and the monogamy of quantum entanglement. We first describe an ideal scheme that is purely deterministic, in the sense that neither party needs to generate any secret randomness at any stage. We also describe a variant that allows the committer to proceed deterministically, requires only local randomness generation from the receiver, and allows the commitment to be verified in the neighborhood of the unveiling point. We show that these schemes still offer near-perfect security in the presence of losses and errors, which can be made perfect if the committer uses an extra single random secret bit. We discuss scenarios where these advantages are significant.
The facets of relativistic quantum field theory
NASA Astrophysics Data System (ADS)
Dosch, H. G.; Müller, V. F.
2010-04-01
Relativistic quantum field theory is generally recognized to form the adequate theoretical frame for subatomic physics, with the Standard Model of Particle Physics as a major achievement. We point out that quantum field theory in its present form is not a monolithic theory, but rather consists of distinct facets, which aim at a common ideal goal. We give a short overview of the strengths and limitations of these facets. We emphasize the theory-dependent relation between the quantum fields, and the basic objects in the empirical domain, the particles. Given the marked conceptual differences between the facets, we argue to view these, and therefore also the Standard Model, as symbolic constructions. We finally note that this view of physical theories originated in the 19th century and is related to the emergence of the classical field as an autonomous concept.
The facets of relativistic quantum field theory
NASA Astrophysics Data System (ADS)
Dosch, H. G.; Müller, V. F.
2011-04-01
Relativistic quantum field theory is generally recognized to form the adequate theoretical frame for subatomic physics, with the Standard Model of Particle Physics as a major achievement. We point out that quantum field theory in its present form is not a monolithic theory, but rather consists of distinct facets, which aim at a common ideal goal. We give a short overview of the strengths and limitations of these facets. We emphasize the theory-dependent relation between the quantum fields, and the basic objects in the empirical domain, the particles. Given the marked conceptual differences between the facets, we argue to view these, and therefore also the Standard Model, as symbolic constructions. We finally note that this view of physical theories originated in the 19th century and is related to the emergence of the classical field as an autonomous concept.
Formulation of the relativistic quantum Hall effect and parity anomaly
NASA Astrophysics Data System (ADS)
Yonaga, Kouki; Hasebe, Kazuki; Shibata, Naokazu
2016-06-01
We present a relativistic formulation of the quantum Hall effect on Haldane sphere. An explicit form of the pseudopotential is derived for the relativistic quantum Hall effect with/without mass term. We clarify particular features of the relativistic quantum Hall states with the use of the exact diagonalization study of the pseudopotential Hamiltonian. Physical effects of the mass term to the relativistic quantum Hall states are investigated in detail. The mass term acts as an interpolating parameter between the relativistic and nonrelativistic quantum Hall effects. It is pointed out that the mass term unevenly affects the many-body physics of the positive and negative Landau levels as a manifestation of the "parity anomaly." In particular, we explicitly demonstrate the instability of the Laughlin state of the positive first relativistic Landau level with the reduction of the charge gap.
Teleportation - Travel in the Quantum and Relativistic Realms and Bejond
NASA Astrophysics Data System (ADS)
Teodorani, M.
2007-01-01
This book, which is devoted to the description and discussion of several methods leading to teleportation, is divided into three main parts: a) foundations of quantum non-locality, quantum particle teleportation and quantum computing; b) foundations of quantum-relativistic teleportation, warp drive propulsion methods and search for extraterrestrial visitation; c) experiments in "psychic teleportation" and problems related to quantum consciousness studies.
Relativistic quantum teleportation with superconducting circuits.
Friis, N; Lee, A R; Truong, K; Sabín, C; Solano, E; Johansson, G; Fuentes, I
2013-03-15
We study the effects of relativistic motion on quantum teleportation and propose a realizable experiment where our results can be tested. We compute bounds on the optimal fidelity of teleportation when one of the observers undergoes nonuniform motion for a finite time. The upper bound to the optimal fidelity is degraded due to the observer's motion. However, we discuss how this degradation can be corrected. These effects are observable for experimental parameters that are within reach of cutting-edge superconducting technology. PMID:25166531
Imperfect relativistic mirrors in the quantum regime
Mendonça, J. T.; Serbeto, A.; Galvão, R. M. O.
2014-05-15
The collective backscattering of intense laser radiation by energetic electron beams is considered in the relativistic quantum regime. Exact solutions for the radiation field are obtained, for arbitrary electron pulse shapes and laser intensities. The electron beams act as imperfect nonlinear mirrors on the incident laser radiation. This collective backscattering process can lead to the development of new sources of ultra-short pulse radiation in the gamma-ray domain. Numerical examples show that, for plausible experimental conditions, intense pulses of gamma-rays, due to the double Doppler shift of the harmonics of the incident laser radiation, can be produced using the available technology, with durations less than 1 as.
Causal localizations in relativistic quantum mechanics
Castrigiano, Domenico P. L. Leiseifer, Andreas D.
2015-07-15
Causal localizations describe the position of quantum systems moving not faster than light. They are constructed for the systems with finite spinor dimension. At the center of interest are the massive relativistic systems. For every positive mass, there is the sequence of Dirac tensor-localizations, which provides a complete set of inequivalent irreducible causal localizations. They obey the principle of special relativity and are fully Poincaré covariant. The boosters are determined by the causal position operator and the other Poincaré generators. The localization with minimal spinor dimension is the Dirac localization. Thus, the Dirac equation is derived here as a mere consequence of the principle of causality. Moreover, the higher tensor-localizations, not known so far, follow from Dirac’s localization by a simple construction. The probability of localization for positive energy states results to be described by causal positive operator valued (PO-) localizations, which are the traces of the causal localizations on the subspaces of positive energy. These causal Poincaré covariant PO-localizations for every irreducible massive relativistic system were, all the more, not known before. They are shown to be separated. Hence, the positive energy systems can be localized within every open region by a suitable preparation as accurately as desired. Finally, the attempt is made to provide an interpretation of the PO-localization operators within the frame of conventional quantum mechanics attributing an important role to the negative energy states.
Balance equations in semi-relativistic quantum hydrodynamics
NASA Astrophysics Data System (ADS)
Ivanov, A. Yu.; Andreev, P. A.; Kuz'menkov, L. S.
2014-05-01
Method of the quantum hydrodynamics has been applied in quantum plasmas studies. As the first step in our consideration, derivation of classical semi-relativistic (i.e., described by the Darwin Lagrangian on microscopic level) hydrodynamical equations is given after a brief review of method development. It provides better distinguishing between classic and quantum semi-relativistic effects. Derivation of the classical equations is interesting since it is made by a natural, but not very widespread method. This derivation contains explicit averaging of the microscopic dynamics. Derivation of corresponding quantum hydrodynamic equations is presented further. Equations are obtained in the five-momentum approximation including the continuity equation, Euler and energy balance equations. It is shown that relativistic corrections lead to presence of new quantum terms in expressions for a force field, a work field etc. The semi-relativistic generalization of the quantum Bohm potential is obtained. Quantum part of the energy current, which is an analog of the quantum Bohm potential for the energy evolution equation, is derived. The Langmuir wave dispersion in semi-relativistic quantum plasmas, corresponding to the Darwin Lagrangian, is also considered to demonstrate contribution of semi-relativistic effects on basic plasma phenomenon.
Quantum time and spatial localization in relativistic quantum mechanics
NASA Astrophysics Data System (ADS)
von Zuben, Francis Stephen Geisler
1999-11-01
Two related problems in relativistic quantum mechanics, the apparent superluminal propagation of initially localized particles, and the dependence of their localization on the motion of the observer, are analyzed in the context of the theory of constraints. Time and energy operators are introduced for the free relativistic particle, and a parametrization invariant formulation is obtained through Dirac constraint theory. The resulting description is of a system constrained in momentum and energy, but not in position or time, for which observables are constants of the motion. The Klein-Gordon equation is recovered on a physical Hilbert space, constructed via integration over the proper time from an augmented Hilbert space, wherein time and energy are dynamical variables. It is shown that the position observable acts on states in the augmented space; those states having strictly positive energy are non-local in time. Localization arises on a particular space-like hyperplane from quantum interference in time, position measurements receiving contributions from the past and future. Apparent causality problems are resolved by noting that, as the particle is potentially in the past, it can propagate to distant regions without exceeding the speed of light. Non-locality of the same system to a moving observer is due to Lorentz rotation of spatial axes out of the interference minimum.
Scattering in the Euclidean formulation of relativistic quantum mechanics
NASA Astrophysics Data System (ADS)
Polyzou, Wayne
2013-10-01
Euclidean relativistic quantum mechanics is a formulation of relativistic quantum mechanics based on the Osterwalder-Schrader reconstruction theorem that exploits the logical independence of locality from the rest of the axioms of Euclidean field theory. I discuss the properties of Euclidean Green functions necessary for the existence of Møller wave operators and the construction of these wave operators in this formalism. Supported by the US Department of Energy, Grant - DE-AC02-81ER40038.
Negative energy waves and quantum relativistic Buneman instabilities.
Haas, F; Eliasson, B; Shukla, P K
2012-09-01
The quantum relativistic Buneman instability is investigated theoretically using a collective Klein-Gordon model for the electrons and a cold fluid model for the ions. The growth rate and unstable wave spectrum is investigated in different parameter regimes corresponding to various degrees of relativistic and quantum effects. The results may be important for streaming instabilities involving ion dynamics in very dense plasmas. PMID:23031033
Irreversible degradation of quantum coherence under relativistic motion
NASA Astrophysics Data System (ADS)
Wang, Jieci; Tian, Zehua; Jing, Jiliang; Fan, Heng
2016-06-01
We study the dynamics of quantum coherence under Unruh thermal noise and seek under which condition the coherence can be frozen in a relativistic setting. We find that the frozen condition is either (i) the initial state is prepared as an incoherence state or (ii) the detectors have no interaction with the external field. That is to say, the decoherence of the detectors' quantum state is irreversible under the influence of thermal noise induced by Unruh radiation. It is shown that quantum coherence approaches zero only in the limit of an infinite acceleration, while quantum entanglement could reduce to zero for a finite acceleration. It is also demonstrated that the robustness of quantum coherence is better than entanglement under the influence of the atom-field interaction for an extremely large acceleration. Therefore, quantum coherence is more robust than entanglement in an accelerating system and the coherence-type quantum resources are more accessible for relativistic quantum information processing tasks.
Alba, David; Crater, Horace W.; Lusanna, Luca
2011-06-15
A new formulation of relativistic quantum mechanics is proposed in the framework of the rest-frame instant form of dynamics, where the world-lines of the particles are parametrized in terms of the Fokker-Pryce center of inertia and of Wigner-covariant relative 3-coordinates inside the instantaneous Wigner 3-spaces, and where there is a decoupled (non-covariant and non-local) canonical relativistic center of mass. This approach: (a) allows us to make a consistent quantization in every inertial frame; (b) leads to a description of both bound and scattering states; (c) offers new insights on the relativistic localization problem; (d) leads to a non-relativistic limit with a Hamilton-Jacobi treatment of the Newton center of mass; (e) clarifies non-local aspects (spatial non-separability) of relativistic entanglement connected with Lorentz signature and not present in its non-relativistic treatment.
Electromagnetic wave equations for relativistically degenerate quantum magnetoplasmas.
Masood, Waqas; Eliasson, Bengt; Shukla, Padma K
2010-06-01
A generalized set of nonlinear electromagnetic quantum hydrodynamic (QHD) equations is derived for a magnetized quantum plasma, including collisional, electron spin- 1/2, and relativistically degenerate electron pressure effects that are relevant for dense astrophysical systems, such as white dwarfs. For illustrative purposes, linear dispersion relations are derived for one-dimensional magnetoacoustic waves for a collisionless nonrelativistic degenerate gas in the presence of the electron spin- 1/2 contribution and for magnetoacoustic waves in a plasma containing relativistically degenerate electrons. It is found that both the spin and relativistic degeneracy at high densities tend to slow down the magnetoacoustic wave due to the Pauli paramagnetic effect and relativistic electron mass increase. The present study outlines the theoretical framework for the investigation of linear and nonlinear behaviors of electromagnetic waves in dense astrophysical systems. The results are applied to calculate the magnetoacoustic speeds for both the nonrelativistic and relativistic electron degeneracy cases typical for white dwarf stars. PMID:20866534
A causal net approach to relativistic quantum mechanics
NASA Astrophysics Data System (ADS)
Bateson, R. D.
2012-05-01
In this paper we discuss a causal network approach to describing relativistic quantum mechanics. Each vertex on the causal net represents a possible point event or particle observation. By constructing the simplest causal net based on Reichenbach-like conjunctive forks in proper time we can exactly derive the 1+1 dimension Dirac equation for a relativistic fermion and correctly model quantum mechanical statistics. Symmetries of the net provide various quantum mechanical effects such as quantum uncertainty and wavefunction, phase, spin, negative energy states and the effect of a potential. The causal net can be embedded in 3+1 dimensions and is consistent with the conventional Dirac equation. In the low velocity limit the causal net approximates to the Schrodinger equation and Pauli equation for an electromagnetic field. Extending to different momentum states the net is compatible with the Feynman path integral approach to quantum mechanics that allows calculation of well known quantum phenomena such as diffraction.
NASA Astrophysics Data System (ADS)
Bauke, Heiko; Klaiber, Michael; Yakaboylu, Enderalp; Hatsagortsyan, Karen Z.; Ahrens, Sven; Müller, Carsten; Keitel, Christoph H.
2013-05-01
Computational methods are indispensable to study the quantum dynamics of relativistic light-matter interactions in parameter regimes where analytical methods become inapplicable. We present numerical methods for solving the time-dependent Dirac equation and the time-dependent Klein-Gordon equation and their implementation on high performance graphics cards. These methods allow us to study tunneling from hydrogen-like highly charged ions in strong laser fields and Kapitza-Dirac scattering in the relativistic regime.
Rehman, M. A.; Qureshi, M. N. S.; Shah, H. A.; Masood, W.
2015-10-15
Nonlinear circularly polarized Alfvén waves are studied in magnetized nonrelativistic, relativistic, and ultrarelativistic degenerate Fermi plasmas. Using the quantum hydrodynamic model, Zakharov equations are derived and the Sagdeev potential approach is used to investigate the properties of the electromagnetic solitary structures. It is seen that the amplitude increases with the increase of electron density in the relativistic and ultrarelativistic cases but decreases in the nonrelativistic case. Both right and left handed waves are considered, and it is seen that supersonic, subsonic, and super- and sub-Alfvénic solitary structures are obtained for different polarizations and under different relativistic regimes.
Processing quantum information with relativistic motion of atoms.
Martín-Martínez, Eduardo; Aasen, David; Kempf, Achim
2013-04-19
We show that particle detectors, such as two-level atoms, in noninertial motion (or in gravitational fields) could be used to build quantum gates for the processing of quantum information. Concretely, we show that through suitably chosen noninertial trajectories of the detectors the interaction Hamiltonian's time dependence can be modulated to yield arbitrary rotations in the Bloch sphere due to relativistic quantum effects. PMID:23679587
Relativistic and quantum electrodynamic effects in superheavy elements
NASA Astrophysics Data System (ADS)
Schwerdtfeger, Peter; Pašteka, Lukáš F.; Punnett, Andrew; Bowman, Patrick O.
2015-12-01
The current status of relativistic electronic structure theory for superheavy elements is reviewed. Recent developments in relativistic quantum theory have made it possible to obtain accurate electronic properties for the trans-actinide elements with the aim to predict their chemical and physical behaviour. The role of quantum electrodynamic effects beyond the no-virtual-pair approximation, which is usually neglected in relativistic molecular calculations, is discussed. Changes in periodic trends due to relativistic effects are outlined for the superheavy elements with nuclear charge Z = 111- 120. We also analyse the role of the negative energy states for the electronic stability of superheavy elements beyond the critical nuclear charge (Zcrit ≈ 170), where the 1s state enters the negative energy continuum at - 2mec2.
Relativistic quantum model of confinement and the current quark masses
NASA Astrophysics Data System (ADS)
Soloviev, L. D.
1998-08-01
We consider a relativistic quantum model of confined massive spinning quarks and antiquarks which describes the leading Regge trajectories of mesons. The quarks are described by the Dirac equations and the gluon contribution is approximated by the Nambu-Goto straight-line string. The string tension and the current quark masses are the main parameters of the model. Additional parameters are phenomenological constants which approximate nonstring short-range contributions. A comparison of the measured meson masses with the model predictions allows one to determine the current quark masses (in MeV) to be ms=227+/-5, mc=1440+/-10, and mb=4715+/-20. The chiral SU3 model makes it possible to estimate from here the u- and d-quark masses to be mu=6.2+/-0.2 Mev and md=11.1+/-0.4 Mev.
Effective photon mass and exact translating quantum relativistic structures
NASA Astrophysics Data System (ADS)
Haas, Fernando; Manrique, Marcos Antonio Albarracin
2016-04-01
Using a variation of the celebrated Volkov solution, the Klein-Gordon equation for a charged particle is reduced to a set of ordinary differential equations, exactly solvable in specific cases. The new quantum relativistic structures can reveal a localization in the radial direction perpendicular to the wave packet propagation, thanks to a non-vanishing scalar potential. The external electromagnetic field, the particle current density, and the charge density are determined. The stability analysis of the solutions is performed by means of numerical simulations. The results are useful for the description of a charged quantum test particle in the relativistic regime, provided spin effects are not decisive.
A hydrodynamical model for relativistic spin quantum plasmas
Asenjo, Felipe A.; Munoz, Victor; Valdivia, J. Alejandro; Mahajan, Swadesh M.
2011-01-15
Based on the one-body particle-antiparticle Dirac theory of electrons, a set of relativistic quantum fluid equations for a spin half plasma is derived. The particle-antiparticle nature of the relativistic particles is explicit in this fluid theory, which also includes quantum effects such as spin. The nonrelativistic limit is shown to be in agreement with previous attempts to develop a spin plasma theory derived from the Pauli Hamiltonian. Harnessing the formalism to the study of electromagnetic mode propagation, conceptually new phenomena are revealed; the particle-antiparticle effects increase the fluid opacity to these waves, while the spin effects tend to make the fluid more transparent.
Unstable particles in non-relativistic quantum mechanics?
Hernandez-Coronado, H.
2011-10-14
The Schroedinger equation is up-to-a-phase invariant under the Galilei group. This phase leads to the Bargmann's superselection rule, which forbids the existence of the superposition of states with different mass and implies that unstable particles cannot be described consistently in non-relativistic quantum mechanics (NRQM). In this paper we claim that Bargmann's rule neglects physical effects and that a proper description of non-relativistic quantum mechanics requires to take into account this phase through the Extended Galilei group and the definition of its action on spacetime coordinates.
Relativistic classical integrable tops and quantum R-matrices
NASA Astrophysics Data System (ADS)
Levin, A.; Olshanetsky, M.; Zotov, A.
2014-07-01
We describe classical top-like integrable systems arising from the quantum exchange relations and corresponding Sklyanin algebras. The Lax operator is expressed in terms of the quantum non-dynamical R-matrix even at the classical level, where the Planck constant plays the role of the relativistic deformation parameter in the sense of Ruijsenaars and Schneider (RS). The integrable systems (relativistic tops) are described as multidimensional Euler tops, and the inertia tensors are written in terms of the quantum and classical R-matrices. A particular case of gl N system is gauge equivalent to the N-particle RS model while a generic top is related to the spin generalization of the RS model. The simple relation between quantum R-matrices and classical Lax operators is exploited in two ways. In the elliptic case we use the Belavin's quantum R-matrix to describe the relativistic classical tops. Also by the passage to the noncommutative torus we study the large N limit corresponding to the relativistic version of the nonlocal 2d elliptic hydrodynamics. Conversely, in the rational case we obtain a new gl N quantum rational non-dynamical R-matrix via the relativistic top, which we get in a different way — using the factorized form of the RS Lax operator and the classical Symplectic Hecke (gauge) transformation. In particular case of gl2 the quantum rational R-matrix is 11-vertex. It was previously found by Cherednik. At last, we describe the integrable spin chains and Gaudin models related to the obtained R-matrix.
Finite- to zero-range relativistic mean-field interactions
Niksic, T.; Vretenar, D.; Lalazissis, G. A.; Ring, P.
2008-03-15
We study the relation between the finite-range (meson-exchange) and zero-range (point-coupling) representations of effective nuclear interactions in the relativistic mean-field framework. Starting from the phenomenological interaction DD-ME2 with density-dependent meson-nucleon couplings, we construct a family of point-coupling effective interactions for different values of the strength parameter of the isoscalar-scalar derivative term. In the meson-exchange picture this corresponds to different values of the {sigma}-meson mass. The parameters of the isoscalar-scalar and isovector-vector channels of the point-coupling interactions are adjusted to nuclear matter and ground-state properties of finite nuclei. By comparing results for infinite and semi-infinite nuclear matter, ground-state masses, charge radii, and collective excitations, we discuss constraints on the parameters of phenomenological point-coupling relativistic effective interaction.
Nonperturbative approach to relativistic quantum communication channels
NASA Astrophysics Data System (ADS)
Landulfo, André G. S.
2016-05-01
We investigate the transmission of both classical and quantum information between two arbitrary observers in globally hyperbolic spacetimes using a quantum field as a communication channel. The field is supposed to be in some arbitrary quasifree state and no choice of representation of its canonical commutation relations is made. Both sender and receiver possess some localized two-level quantum system with which they can interact with the quantum field to prepare the input and receive the output of the channel, respectively. The interaction between the two-level systems and the quantum field is such that one can trace out the field degrees of freedom exactly and thus obtain the quantum channel in a nonperturbative way. We end the paper determining the unassisted as well as the entanglement-assisted classical and quantum channel capacities.
Relativistic Quantum Bayesian Game Under Decoherence
NASA Astrophysics Data System (ADS)
Situ, Haozhen; Huang, Zhiming
2016-05-01
We study how Unruh effect and quantum noise affect the payoffs of a quantum conflicting interest Bayesian game. Three types of noisy channels, i.e., the amplitude damping channel, the depolarizing channel and the phase damping channel, are employed to model the decoherence processes. We find that Unruh effect weakens the payoffs in the quantum game and the quantum payoffs are lower than the classical payoffs when the acceleration parameter is large enough. However, the variation of the payoffs with the decoherence parameter is not always monotonic. Sometimes more decoherence may lead to higher payoffs.
Relativistic wavepackets in classically chaotic quantum cosmological billiards
NASA Astrophysics Data System (ADS)
Koehn, Michael
2012-03-01
Close to a spacelike singularity, pure gravity and supergravity in 4 to 11 spacetime dimensions admit a cosmological billiard description based on hyperbolic Kac-Moody groups. We investigate the quantum cosmological billiards of relativistic wavepackets towards the singularity, employing flat and hyperbolic space descriptions for the quantum billiards. We find that the strongly chaotic classical billiard motion of four-dimensional pure gravity corresponds to a spreading wavepacket subject to successive redshifts and tending to zero as the singularity is approached. We discuss the possible implications of these results in the context of singularity resolution and compare them with those of known semiclassical approaches. As an aside, we obtain exact solutions for the one-dimensional relativistic quantum billiards with moving walls.
Dirac particle in a box, and relativistic quantum Zeno dynamics
NASA Astrophysics Data System (ADS)
Menon, Govind; Belyi, Sergey
2004-09-01
After developing a complete set of eigenfunctions for a Dirac particle restricted to a box, the quantum Zeno dynamics of a relativistic system is considered. The evolution of a continuously observed quantum mechanical system is governed by the theorem put forth by Misra and Sudarshan. One of the conditions for quantum Zeno dynamics to be manifest is that the Hamiltonian is semi-bounded. This Letter analyzes the effects of continuous observation of a particle whose time evolution is generated by the Dirac Hamiltonian. The theorem by Misra and Sudarshan is not applicable here since the Dirac operator is not semi-bounded.
Foundations for proper-time relativistic quantum theory
NASA Astrophysics Data System (ADS)
Gill, Tepper L.; Morris, Trey; Kurtz, Stewart K.
2015-05-01
This paper is a progress report on the foundations for the canonical proper-time approach to relativistic quantum theory. We first review the the standard square-root equation of relativistic quantum theory, followed by a review of the Dirac equation, providing new insights into the physical properties of both. We then introduce the canonical proper-time theory. For completeness, we give a brief outline of the canonical proper-time approach to electrodynamics and mechanics, and then introduce the canonical proper-time approach to relativistic quantum theory. This theory leads to three new relativistic wave equations. In each case, the canonical generator of proper-time translations is strictly positive definite, so that it represents a particle. We show that the canonical proper-time extension of the Dirac equation for Hydrogen gives results that are consistently closer to the experimental data, when compared to the Dirac equation. However, these results are not sufficient to account for either the Lamb shift or the anomalous magnetic moment.
Relativistic Quantum Metrology in Open System Dynamics
Tian, Zehua; Wang, Jieci; Fan, Heng; Jing, Jiliang
2015-01-01
Quantum metrology studies the ultimate limit of precision in estimating a physical quantity if quantum strategies are exploited. Here we investigate the evolution of a two-level atom as a detector which interacts with a massless scalar field using the master equation approach for open quantum system. We employ local quantum estimation theory to estimate the Unruh temperature when probed by a uniformly accelerated detector in the Minkowski vacuum. In particular, we evaluate the Fisher information (FI) for population measurement, maximize its value over all possible detector preparations and evolution times, and compare its behavior with that of the quantum Fisher information (QFI). We find that the optimal precision of estimation is achieved when the detector evolves for a long enough time. Furthermore, we find that in this case the FI for population measurement is independent of initial preparations of the detector and is exactly equal to the QFI, which means that population measurement is optimal. This result demonstrates that the achievement of the ultimate bound of precision imposed by quantum mechanics is possible. Finally, we note that the same configuration is also available to the maximum of the QFI itself. PMID:25609187
Relativistic quantum games in noninertial frames
NASA Astrophysics Data System (ADS)
Khan, Salman; Khalid Khan, M.
2011-09-01
We study the influence of the Unruh effect on quantum non-zero sum games. In particular, we investigate the quantum Prisoners’ Dilemma both for entangled and unentangled initial states and show that the acceleration of the noninertial frames disturbs the symmetry of the game. It is shown that for the maximally entangled initial state, the classical strategy \\hat{C} (cooperation) becomes the dominant strategy. Our investigation shows that any quantum strategy does no better for any player against the classical strategies. The miracle move of Eisert et al (1999 Phys. Rev. Lett.83 3077) is no more a superior move. We show that the dilemma-like situation is resolved in favor of one player or the other.
Which is the quantum decay law of relativistic particles?
NASA Astrophysics Data System (ADS)
Alavi, S. A.; Giunti, C.
2015-03-01
We discuss the relation between the quantum-mechanical survival probability of an unstable system in motion and that of the system at rest. The usual definition of the survival probability which takes into account only the time evolution of an unstable system leads to a relation between the survival probability of the system in motion and that of the system at rest which is different from the standard relation based on relativistic time dilation. This approach led other authors to claim non-standard quantum-mechanical effects which are in clear contradiction with Special Relativity. We show that an appropriate relativistic definition of the survival probability which takes into account also the space evolution of an unstable system leads to the standard relation between the survival probability of the system in motion and that of the system at rest, in agreement with Special Relativity. We present a rigorous derivation of this result based on a wave packet treatment.
Quantization of Relativistic action in multiples of Planck's (constant) Quantum of action
NASA Astrophysics Data System (ADS)
Estakhr, Ahmad Reza
2013-04-01
Quantization of Relativistic action in multiples of Planck's (constant) Quantum of action. a new Postulate for special relativity theory. The third Postulate of special relativity: Relativistic action is limited to Planck's Quantum of action. S=^tftiLdt=n.h n Z. where the L=-moc^2^amp;-1, is the Lagrangian. action for a point particle in a curved spacetime. S =-Mc ds = -Mc ξ0^ξ1√gμν(x)dx^μ(ξ)dξ dx^ν(ξ)dξ dξ=nh Quantization of Nambu-Goto action: S = -12πα' d^2 σ√X ^2 - X'^2 = nh n Z. point: The action S= - E0 δτ of a relativistic particle is minus the rest energy E0=m0c^2 times the change δτ=τf-τi in proper time. Single relativistic particle When relativistic effects are significant, the action of a point particle of mass ``m'' travelling a world line ``C'' parametrized by the proper time τ is :S = - moc^2 C,τ. If instead, the particle is parametrized by the coordinate time ''t'' of the particle and the coordinate time ranges from t1 to t2, then the action becomes :t1^t2L ,t where the Lagrangian is :L = - moc^2 √1 - v^2c^2.
Resolution of the Klein Paradox within Relativistic Quantum Mechanics
Alhaidari, A. D.
2011-10-27
We present a resolution of the Klein paradox within the framework of one-particle relativistic quantum mechanics (no pair production). Not only reflection becomes total but the vacuum remains neutral as well. This is accomplished by replacing the pair production process with virtual negative energy ''incidence'' within the barrier in a process analogous to the introduction of image charges in electrostatic and virtual sources in optics.
Absorbing boundary conditions for relativistic quantum mechanics equations
Antoine, X.; Sater, J.; Fillion-Gourdeau, F.; Bandrauk, A.D.
2014-11-15
This paper is devoted to the derivation of absorbing boundary conditions for the Klein–Gordon and Dirac equations modeling quantum and relativistic particles subject to classical electromagnetic fields. Microlocal analysis is the main ingredient in the derivation of these boundary conditions, which are obtained in the form of pseudo-differential equations. Basic numerical schemes are derived and analyzed to illustrate the accuracy of the derived boundary conditions.
Spacetime alternatives in the quantum mechanics of a relativistic particle
Whelan, J.T. Isaac Newton Institute for Mathematical Sciences, 20 Clarkson Road, Cambridge, CB3 0EH )
1994-11-15
Hartle's generalized quantum mechanics formalism is used to examine spacetime coarse grainings, i.e., sets of alternatives defined with respect to a region extended in time as well as space, in the quantum mechanics of a free relativistic particle. For a simple coarse graining and suitable initial conditions, tractable formulas are found for branch wave functions. Despite the nonlocality of the positive-definite version of the Klein-Gordon inner product, which means that nonoverlapping branches are not sufficient to imply decoherence, some initial conditions are found to give decoherence and allow the consistent assignment of probabilities.
Charged and Electromagnetic Fields from Relativistic Quantum Geometry
NASA Astrophysics Data System (ADS)
Arcodía, Marcos; Bellini, Mauricio
2016-06-01
In the Relativistic Quantum Geometry (RQG) formalism recently introduced, was explored the possibility that the variation of the tensor metric can be done in a Weylian integrable manifold using a geometric displacement, from a Riemannian to a Weylian integrable manifold, described by the dynamics of an auxiliary geometrical scalar field $\\theta$, in order that the Einstein tensor (and the Einstein equations) can be represented on a Weyl-like manifold. In this framework we study jointly the dynamics of electromagnetic fields produced by quantum complex vector fields, which describes charges without charges. We demonstrate that complex fields act as a source of tetra-vector fields which describe an extended Maxwell dynamics.
Linear and nonlinear wave propagation in weakly relativistic quantum plasmas
Stefan, Martin; Brodin, Gert
2013-01-15
We consider a recently derived kinetic model for weakly relativistic quantum plasmas. We find that that the effects of spin-orbit interaction and Thomas precession may alter the linear dispersion relation for a magnetized plasma in case of high plasma densities and/or strong magnetic fields. Furthermore, the ponderomotive force induced by an electromagnetic pulse is studied for an unmagnetized plasma. It turns out that for this case the spin-orbit interaction always gives a significant contribution to the quantum part of the ponderomotive force.
Multiple-event probability in general-relativistic quantum mechanics
Hellmann, Frank; Mondragon, Mauricio; Perez, Alejandro; Rovelli, Carlo
2007-04-15
We discuss the definition of quantum probability in the context of 'timeless' general-relativistic quantum mechanics. In particular, we study the probability of sequences of events, or multievent probability. In conventional quantum mechanics this can be obtained by means of the 'wave function collapse' algorithm. We first point out certain difficulties of some natural definitions of multievent probability, including the conditional probability widely considered in the literature. We then observe that multievent probability can be reduced to single-event probability, by taking into account the quantum nature of the measuring apparatus. In fact, by exploiting the von-Neumann freedom of moving the quantum/classical boundary, one can always trade a sequence of noncommuting quantum measurements at different times, with an ensemble of simultaneous commuting measurements on the joint system+apparatus system. This observation permits a formulation of quantum theory based only on single-event probability, where the results of the wave function collapse algorithm can nevertheless be recovered. The discussion also bears on the nature of the quantum collapse.
Noisy relativistic quantum games in noninertial frames
NASA Astrophysics Data System (ADS)
Khan, Salman; Khan, M. Khalid
2013-02-01
The influence of noise and of Unruh effect on quantum Prisoners' dilemma is investigated both for entangled and unentangled initial states. The noise is incorporated through amplitude damping channel. For unentangled initial state, the decoherence compensates for the adverse effect of acceleration of the frame and the effect of acceleration becomes irrelevant provided the game is fully decohered. It is shown that the inertial player always out scores the noninertial player by choosing defection. For maximally entangled initially state, we show that for fully decohered case every strategy profile results in either of the two possible equilibrium outcomes. Two of the four possible strategy profiles become Pareto optimal and Nash equilibrium and no dilemma is leftover. It is shown that other equilibrium points emerge for different region of values of decoherence parameter that are either Pareto optimal or Pareto inefficient in the quantum strategic spaces. It is shown that the Eisert et al. (Phys Rev Lett 83:3077, 1999) miracle move is a special move that leads always to distinguishable results compare to other moves. We show that the dilemma like situation is resolved in favor of one player or the other.
A signed particle formulation of non-relativistic quantum mechanics
Sellier, Jean Michel
2015-09-15
A formulation of non-relativistic quantum mechanics in terms of Newtonian particles is presented in the shape of a set of three postulates. In this new theory, quantum systems are described by ensembles of signed particles which behave as field-less classical objects which carry a negative or positive sign and interact with an external potential by means of creation and annihilation events only. This approach is shown to be a generalization of the signed particle Wigner Monte Carlo method which reconstructs the time-dependent Wigner quasi-distribution function of a system and, therefore, the corresponding Schrödinger time-dependent wave-function. Its classical limit is discussed and a physical interpretation, based on experimental evidences coming from quantum tomography, is suggested. Moreover, in order to show the advantages brought by this novel formulation, a straightforward extension to relativistic effects is discussed. To conclude, quantum tunnelling numerical experiments are performed to show the validity of the suggested approach.
Relativistic laser-plasma interactions in the quantum regime.
Eliasson, Bengt; Shukla, P K
2011-04-01
We consider nonlinear interactions between a relativistically strong laser beam and a plasma in the quantum regime. The collective behavior of electrons is modeled by a Klein-Gordon equation, which is nonlinearly coupled with the electromagnetic wave through the Maxwell and Poisson equations. This allows us to study nonlinear interactions between arbitrarily large-amplitude electromagnetic waves and a quantum plasma. We have used our system of nonlinear equations to study theoretically the parametric instabilities involving stimulated Raman scattering and modulational instabilities. A model for quasi-steady-state propagating electromagnetic wave packets is also derived, and which shows possibility of localized solitary structures in a quantum plasma. Numerical simulations demonstrate collapse and acceleration of electrons in the nonlinear stage of the modulational instability, as well as possibility of the wake-field acceleration of electrons to relativistic speeds by short laser pulses at nanometer length scales. Our study is relevant for understanding the localization of intense electromagnetic pulses in a quantum plasma with extremely high electron densities and relatively low temperature. PMID:21599316
Foundations of a spacetime path formalism for relativistic quantum mechanics
Seidewitz, Ed
2006-11-15
Quantum field theory is the traditional solution to the problems inherent in melding quantum mechanics with special relativity. However, it has also long been known that an alternative first-quantized formulation can be given for relativistic quantum mechanics, based on the parametrized paths of particles in spacetime. Because time is treated similarly to the three space coordinates, rather than as an evolution parameter, such a spacetime approach has proved particularly useful in the study of quantum gravity and cosmology. This paper shows how a spacetime path formalism can be considered to arise naturally from the fundamental principles of the Born probability rule, superposition, and Poincare invariance. The resulting formalism can be seen as a foundation for a number of previous parametrized approaches in the literature, relating, in particular, 'off-shell' theories to traditional on-shell quantum field theory. It reproduces the results of perturbative quantum field theory for free and interacting particles, but provides intriguing possibilities for a natural program for regularization and renormalization. Further, an important consequence of the formalism is that a clear probabilistic interpretation can be maintained throughout, with a natural reduction to nonrelativistic quantum mechanics.
Optical-model potential in a relativistic quantum field model
NASA Astrophysics Data System (ADS)
Jaminon, M.; Mahaux, C.; Rochus, P.
1980-11-01
The average nucleon-nucleus potential at low and medium energy is investigated in the framework of a relativistic quantum field model. Using the same input parameters as Brockmann in his recent study of nuclear ground states, we calculate the self-consistent relativistic Hartree potential at positive energy in the case of infinite nuclear matter and of 16O and 40Ca. This potential is the sum of a scalar operator and of the fourth component of a vector operator. We construct its Schrödinger-equivalent potential by eliminating the small component of the Dirac spinor. The central part of this Schrödinger-equivalent potential is in fair agreement with empirical values at low and intermediate energy. Particular attention is paid to the intermediate energy domain, in which the calculated potential is repulsive in the nuclear interior and attractive at the nuclear surface. This is in keeping with some empirical evidence and is similar to results found in the framework of the nonrelativistic Brueckner-Hartree-Fock approximation. The spin-orbit potential of the relativistic Hartree model is also in good agreement with empirical values. NUCLEAR REACTIONS Calculated average nuclear field of nuclear matter, 16O and 40Ca at positive energy from relativistic Hartree approximation.
Volkov solutions for relativistic quantum plasmas
Mendonca, J. T.; Serbeto, A.
2011-02-15
This work studies the electron quantum states, as determined by the Dirac equation, in the field of electrostatic and electromagnetic waves in a plasma. We discuss the main differences with respect to the vacuum case, and the assumptions under which the vacuum Volkov solutions can be adapted to a plasma. The case of ultrashort electromagnetic wave pulses is also discussed. We also consider the electron states in the field of an electron plasma wave. Modified Volkov solutions of the Dirac equation can also be found. For electron plasma waves such that the phase velocity becomes close to the speed of light, these solutions are exact. Finally, we consider electron states in the field of two waves in a plasma, with relevance to the mixed case where one of the waves is electrostatic and the other is electromagnetic.
Langmuir waves in semi-relativistic spinless quantum plasmas
NASA Astrophysics Data System (ADS)
Ivanov, A. Yu.; Andreev, P. A.; Kuzmenkov, L. S.
2015-06-01
Many-particle quantum hydrodynamics based on the Darwin Hamiltonian (the Hamiltonian corresponding to the Darwin Lagrangian) is considered. A force field appearing in the corresponding Euler equation is considered in detail. Contributions from different terms of the Darwin Hamiltonian in the Euler equation are traced. For example, the relativistic correction to the kinetic energy of particles leads to several terms in the Euler equation; these terms have different form. One of them has a form similar to a term appearing from the Darwin term. Hence, the two different mechanisms give analogous contributions in wave dispersion. A microscopic analog of the Biot-Savart law, called the current-current interaction, describing an interaction of moving charges via the magnetic field, is also included in our description. The semi-relativistic generalization of the quantum Bohm potential is obtained. Contribution of the relativistic effects in the spectrum of plasma collective excitations is considered. The contributions of the spin-spin, spin-current, and spin-orbit interactions in this model are considered. The contribution of the spin evolution in the Langmuir wave spectrum is calculated at the propagation of wave perpendicular to the external magnetic field.
Relativistic Quantum Communication and the Structure of Spacetime
NASA Astrophysics Data System (ADS)
Martin-Martinez, Eduardo
We study the transmission of information and correlations through quantum fields in cosmological backgrounds. With this aim, we make use of quantum information tools to quantify the classical and quantum correlations induced by a quantum massless scalar field in two particle detectors, one located in the early universe (Alice's) and the other located at a later time (Bob's). In particular, we focus on two phenomena: a) the consequences on the transmission of information of the violations of the strong Huygens principle for quantum fields, and b) the analysis of the field vacuum correlations via correlation harvesting from Alice to Bob. We will study a standard cosmological model first and then assess whether these results also hold if we use other than the general relativistic dynamics. As a particular example, we will study the transmission of information through the Big Bounce, that replaces the Big Bang, in the effective dynamics of Loop Quantum Cosmology. We show that much more information reaches us through timelike channels (not mediated by real photons) than it is carried by rays of light, which are usually regarded as the only carriers of information.
Stationary self-focusing of Gaussian laser beam in relativistic thermal quantum plasma
Patil, S. D.; Takale, M. V.
2013-07-15
In the present paper, we have employed the quantum dielectric response in thermal quantum plasma to model relativistic self-focusing of Gaussian laser beam in a plasma. We have presented an extensive parametric investigation of the dependence of beam-width parameter on distance of propagation in relativistic thermal quantum plasma. We have studied the role of Fermi temperature in the phenomenon of self-focusing. It is found that the quantum effects cause much higher oscillations of beam-width parameter and better relativistic focusing of laser beam in thermal quantum plasma in comparison with that in the relativistic cold quantum plasma and classical relativistic plasma. Our computations show more reliable results in comparison to the previous works.
A finite Zitterbewegung model for relativistic quantum mechanics
Noyes, H.P.
1990-02-19
Starting from steps of length h/mc and time intervals h/mc{sup 2}, which imply a quasi-local Zitterbewegung with velocity steps {plus minus}c, we employ discrimination between bit-strings of finite length to construct a necessary 3+1 dimensional event-space for relativistic quantum mechanics. By using the combinatorial hierarchy to label the strings, we provide a successful start on constructing the coupling constants and mass ratios implied by the scheme. Agreement with experiments is surprisingly accurate. 22 refs., 1 fig.
``Simplest Molecule'' Clarifies Modern Physics II. Relativistic Quantum Mechanics
NASA Astrophysics Data System (ADS)
Harter, William; Reimer, Tyle
2015-05-01
A ``simplest molecule'' consisting of CW- laser beam pairs helps to clarify relativity from poster board - I. In spite of a seemingly massless evanescence, an optical pair also clarifies classical and quantum mechanics of relativistic matter and antimatter. Logical extension of (x,ct) and (ω,ck) geometry gives relativistic action functions of Hamiltonian, Lagrangian, and Poincare that may be constructed in a few ruler-and-compass steps to relate relativistic parameters for group or phase velocity, momentum, energy, rapidity, stellar aberration, Doppler shifts, and DeBroglie wavelength. This exposes hyperbolic and circular trigonometry as two sides of one coin connected by Legendre contact transforms. One is Hamiltonian-like with a longitudinal rapidity parameter ρ (log of Doppler shift). The other is Lagrange-like with a transverse angle parameter σ (stellar aberration). Optical geometry gives recoil in absorption, emission, and resonant Raman-Compton acceleration and distinguishes Einstein rest mass, Galilean momentum mass, and Newtonian effective mass. (Molecular photons appear less bullet-like and more rocket-like.) In conclusion, modern space-time physics appears as a simple result of the more self-evident Evenson's axiom: ``All colors go c.''
"simplest Molecule" Clarifies Modern Physics II. Relativistic Quantum Mechanics
NASA Astrophysics Data System (ADS)
Reimer, T. C.; Harter, W. G.
2014-06-01
A "simplest molecule" consisting of CW-laser beam pairs helps to clarify relativity in Talk I. In spite of a seemingly massless evanescence, an optical pair also clarifies classical and quantum mechanics of relativistic matter and anti-matter. *Logical extension of (x,ct) and (ω,ck) geometry gives relativistic action functions of Hamiltonian, Lagrangian, and Poincare that may be constructed in a few ruler-and-compass steps to relate relativistic parameters for group or phase velocity, momentum, energy, rapidity, stellar aberration, Doppler shifts, and DeBroglie wavelength. This exposes hyperbolic and circular trigonometry as two sides of one coin connected by Legendre contact transforms. One is Hamiltonian-like with a longitudinal rapidity parameter ρ (log of Doppler shift). The other is Lagrange-like with a transverse angle parameter σ (stellar aberration). Optical geometry gives recoil in absorption, emission, and resonant Raman-Compton acceleration and distinguishes Einstein rest mass, Galilean momentum mass, and Newtonian effective mass. (Molecular photons appear less bullet-like and more rocket-like.) In conclusion, modern space-time physics appears as a simple result of the more self-evident Evenson's axiom: "All colors go c."
Atomic electron energies including relativistic effects and quantum electrodynamic corrections
NASA Technical Reports Server (NTRS)
Aoyagi, M.; Chen, M. H.; Crasemann, B.; Huang, K. N.; Mark, H.
1977-01-01
Atomic electron energies have been calculated relativistically. Hartree-Fock-Slater wave functions served as zeroth-order eigenfunctions to compute the expectation of the total Hamiltonian. A first order correction to the local approximation was thus included. Quantum-electrodynamic corrections were made. For all orbitals in all atoms with 2 less than or equal to Z less than or equal to 106, the following quantities are listed: total energies, electron kinetic energies, electron-nucleus potential energies, electron-electron potential energies consisting of electrostatic and Breit interaction (magnetic and retardation) terms, and vacuum polarization energies. These results will serve for detailed comparison of calculations based on other approaches. The magnitude of quantum electrodynamic corrections is exhibited quantitatively for each state.
Can relativistic bit commitment lead to secure quantum oblivious transfer?
NASA Astrophysics Data System (ADS)
He, Guang Ping
2015-05-01
While unconditionally secure bit commitment (BC) is considered impossible within the quantum framework, it can be obtained under relativistic or experimental constraints. Here we study whether such BC can lead to secure quantum oblivious transfer (QOT). The answer is not completely negative. In one hand, we provide a detailed cheating strategy, showing that the "honest-but-curious adversaries" in some of the existing no-go proofs on QOT still apply even if secure BC is used, enabling the receiver to increase the average reliability of the decoded value of the transferred bit. On the other hand, it is also found that some other no-go proofs claiming that a dishonest receiver can always decode all transferred bits simultaneously with reliability 100% become invalid in this scenario, because their models of cryptographic protocols are too ideal to cover such a BC-based QOT.
Causality and quantum criticality in long-range lattice models
NASA Astrophysics Data System (ADS)
Maghrebi, Mohammad F.; Gong, Zhe-Xuan; Foss-Feig, Michael; Gorshkov, Alexey V.
2016-03-01
Long-range quantum lattice systems often exhibit drastically different behavior than their short-range counterparts. In particular, because they do not satisfy the conditions for the Lieb-Robinson theorem, they need not have an emergent relativistic structure in the form of a light cone. Adopting a field-theoretic approach, we study the one-dimensional transverse-field Ising model with long-range interactions, and a fermionic model with long-range hopping and pairing terms, explore their critical and near-critical behavior, and characterize their response to local perturbations. We deduce the dynamic critical exponent, up to the two-loop order within the renormalization group theory, which we then use to characterize the emergent causal behavior. We show that beyond a critical value of the power-law exponent of the long-range couplings, the dynamics effectively becomes relativistic. Various other critical exponents describing correlations in the ground state, as well as deviations from a linear causal cone, are deduced for a wide range of the power-law exponent.
Solution of relativistic quantum optics problems using clusters of graphical processing units
Gordon, D.F. Hafizi, B.; Helle, M.H.
2014-06-15
Numerical solution of relativistic quantum optics problems requires high performance computing due to the rapid oscillations in a relativistic wavefunction. Clusters of graphical processing units are used to accelerate the computation of a time dependent relativistic wavefunction in an arbitrary external potential. The stationary states in a Coulomb potential and uniform magnetic field are determined analytically and numerically, so that they can used as initial conditions in fully time dependent calculations. Relativistic energy levels in extreme magnetic fields are recovered as a means of validation. The relativistic ionization rate is computed for an ion illuminated by a laser field near the usual barrier suppression threshold, and the ionizing wavefunction is displayed.
Quantum diffusion of a relativistic particle in a time-dependent random potential.
Sepehrinia, Reza
2015-04-01
We present a rigorous study of quantum diffusion of a relativistic particle subjected to a time-dependent random potential with δ correlation in time. We find that in the asymptotic time limit the particle wave packet spreads ballistically in contrast with the nonrelativistic case, which in the same situation exhibits superballistic diffusion. The relativistic suppression of wave packet diffusion is discussed in connection with statistical conservation laws that follow from relativistic dynamics. PMID:25974441
A dynamical time operator in Dirac's relativistic quantum mechanics
NASA Astrophysics Data System (ADS)
Bauer, M.
2014-03-01
A self-adjoint dynamical time operator is introduced in Dirac's relativistic formulation of quantum mechanics and shown to satisfy a commutation relation with the Hamiltonian analogous to that of the position and momentum operators. The ensuing time-energy uncertainty relation involves the uncertainty in the instant of time when the wave packet passes a particular spatial position and the energy uncertainty associated with the wave packet at the same time, as envisaged originally by Bohr. The instantaneous rate of change of the position expectation value with respect to the simultaneous expectation value of the dynamical time operator is shown to be the phase velocity, in agreement with de Broglie's hypothesis of a particle associated wave whose phase velocity is larger than c. Thus, these two elements of the original basis and interpretation of quantum mechanics are integrated into its formal mathematical structure. Pauli's objection is shown to be resolved or circumvented. Possible relevance to current developments in electron channeling, in interference in time, in Zitterbewegung-like effects in spintronics, graphene and superconducting systems and in cosmology is noted.
NASA Astrophysics Data System (ADS)
Binz, Ernst; Schempp, Walter
2001-06-01
Quantum holography is a well established theory of mathematical physics based on harmonic analysis on the Heisenberg Lie group G. The geometric quantization is performed by projectivization of the complexified coadjoint orbit picture of the unitary dual Ĝ of G in order to achieve a geometric adjustment of the quantum scenario to special relativity theory. It admits applications to various imaging modalities such as synthetic aperture radar (SAR) in the microwave range, and, most importantly for the field of non-invasive medical diagnosis, to the clinical imaging modality of magnetic resonance tomography (MRI) in the radio frequency range. Quantum holography explains the quantum teleportation phenomemon through Einstein-Podolsky-Rosen (EPR) channels which is a consequence of the non-locality of phase coherent quantum field theory, the concept of absolute simultaneity of special relativity theory which provides the Einstein equivalence of energy and Fitzgerald-Lorentz dilated mass, and the perfect quantum holographic replication process of molecular genetic information processing. It specifically reveals what was before unobservable in quantum optics, namely the interference phenomena of matter wavelets of Bose-Einstein condensates, and what was before unobservable in special relativity, namely the light in flight (LIF) recording processing by ultrafast laser pulse trains. Finally, it provides a Lie group theoretical approach to the Kruskal coordinatized Schwarzschild manifold of relativistic cosmology with large scale applications to general relativity theory such as gravitational instanton symmetries and the theory of black holes. The direct spinorial detection of gravitational wavelets emitted by the binary radio pulsar PSR 1913+16 and known only by anticipatory system computation so far will also be based on the principles of quantum holography applied to very large array (VLA) radio interferometers. .
Trajectories and causal phase-space approach to relativistic quantum mechanics
Holland, P.R.; Kyprianidis, A.; Vigier, J.P.
1987-05-01
The authors analyze phase-space approaches to relativistic quantum mechanics from the viewpoint of the causal interpretation. In particular, they discuss the canonical phase space associated with stochastic quantization, its relation to Hilbert space, and the Wigner-Moyal formalism. They then consider the nature of Feynman paths, and the problem of nonlocality, and conclude that a perfectly consistent relativistically covariant interpretation of quantum mechanics which retains the notion of particle trajectory is possible.
Quantum Correlations of Two Relativistic Spin-{1}/{2} Particles Under Noisy Channels
NASA Astrophysics Data System (ADS)
Mahdian, M.; Mojaveri, B.; Dehghani, A.; Makaremi, T.
2016-02-01
We study the quantum correlation dynamics of bipartite spin-{1}/{2} density matrices for two particles under Wigner rotations induced by Lorentz transformations which is transmitted through noisy channels. We compare quantum entanglement, geometric discord(GD), and quantum discord (QD) for bipartite relativistic spin-{1}/{2} states under noisy channels. We find out QD and GD tend to death asymptotically but a sudden change in the decay rate of the entanglement occurs under noisy channels. Also, bipartite relativistic spin density matrices are considered as a quantum channel for teleportation one-qubit state under the influence of depolarizing noise and compare fidelity for various velocities of observers.
Quantum mechanics in noninertial reference frames: Relativistic accelerations and fictitious forces
NASA Astrophysics Data System (ADS)
Klink, W. H.; Wickramasekara, S.
2016-06-01
One-particle systems in relativistically accelerating reference frames can be associated with a class of unitary representations of the group of arbitrary coordinate transformations, an extension of the Wigner-Bargmann definition of particles as the physical realization of unitary irreducible representations of the Poincaré group. Representations of the group of arbitrary coordinate transformations become necessary to define unitary operators implementing relativistic acceleration transformations in quantum theory because, unlike in the Galilean case, the relativistic acceleration transformations do not themselves form a group. The momentum operators that follow from these representations show how the fictitious forces in noninertial reference frames are generated in quantum theory.
Quantum Features of PXRC Angular Distributions From Relativistic Channeled Electrons in a Crystal
NASA Astrophysics Data System (ADS)
Korotchenko, K. B.; Pivovarov, Yu L.
2014-05-01
We predict quantum features in angular distributions of parametric X-radiation from channeled relativistic electrons (PXRC). The effect is connected with the number of quantum states of channeled electrons, form-factors of the transverse quantum channeling states and initial populations of these quantum states. The main motivation of this work is theoretical prediction for the future experiment at the SAGA-LS facility.
NASA Astrophysics Data System (ADS)
Rohrlich, Daniel
Y. Aharonov and A. Shimony both conjectured that two axioms - relativistic causality (``no superluminal signalling'') and nonlocality - so nearly contradict each other that only quantum mechanics reconciles them. Can we indeed derive quantum mechanics, at least in part, from these two axioms? No: ``PR-box'' correlations show that quantum correlations are not the most nonlocal correlations consistent with relativistic causality. Here we replace ``nonlocality'' with ``retrocausality'' and supplement the axioms of relativistic causality and retrocausality with a natural and minimal third axiom: the existence of a classical limit, in which macroscopic observables commute. That is, just as quantum mechanics has a classical limit, so must any generalization of quantum mechanics. In this limit, PR-box correlations violaterelativistic causality. Generalized to all stronger-than-quantum bipartite correlations, this result is a derivation of Tsirelson's bound (a theorem of quantum mechanics) from the three axioms of relativistic causality, retrocausality and the existence of a classical limit. Although the derivation does not assume quantum mechanics, it points to the Hilbert space structure that underlies quantum correlations. I thank the John Templeton Foundation (Project ID 43297) and the Israel Science Foundation (Grant No. 1190/13) for support.
Classical limit of relativistic quantum mechanical equations in the Foldy-Wouthuysen representation
NASA Astrophysics Data System (ADS)
Silenko, A. Ya.
2013-03-01
It is shown that, under the Wentzel-Kramers-Brillouin approximation conditions, using the Foldy-Wouthuysen (FW) representation allows the problem of finding a classical limit of relativistic quantum mechanical equations to be reduced to the replacement of operators in the Hamiltonian and quantum mechanical equations of motion by the respective classical quantities.
Acceleration of positrons by a relativistic electron beam in the presence of quantum effects
Niknam, A. R.; Aki, H.; Khorashadizadeh, S. M.
2013-09-15
Using the quantum magnetohydrodynamic model and obtaining the dispersion relation of the Cherenkov and cyclotron waves, the acceleration of positrons by a relativistic electron beam is investigated. The Cherenkov and cyclotron acceleration mechanisms of positrons are compared together. It is shown that growth rate and, therefore, the acceleration of positrons can be increased in the presence of quantum effects.
The role of shape invariance potentials in the relativistic quantum mechanics
NASA Astrophysics Data System (ADS)
Bakhshi, Z.; Panahi, H.
2016-05-01
The point canonical transformation in non-relativistic quantum mechanics is applied as an algebraic method to obtain the solutions of the Dirac equation with spherical symmetry electromagnetic potentials. We want to show that some of the non-relativistic solvable potentials with shape-invariant symmetry can be related to the radial Dirac equation. Using this method, the idea of supersymmetry and shape invariance can be expanded to the relativistic quantum mechanics. The spinor wave functions for some of the obtained four-component electromagnetic potential are given in terms of special functions such as Jacobi, generalized Laguerre and Hermite polynomials. The relativistic bound-states spectrum for each case is also calculated in terms of the bound-states spectrum of the solvable potentials.
NASA Astrophysics Data System (ADS)
Zhu, Zhenni; Wu, Zhengwei; Li, Chunhua; Yang, Weihong
2014-11-01
A model for the nonlinear properties of obliquely propagating electron acoustic solitary waves in a two-electron populated relativistically quantum magnetized plasma is presented. By using the standard reductive perturbation technique, the Zakharov-Kuznetsov (ZK) equation is derived and this equation gives the solitary wave solution. It is observed that the relativistic effects, the ratio of the cold to hot electron unperturbed number density and the magnetic field normalized by electron cyclotron frequency significantly influence the solitary structures.
NASA Astrophysics Data System (ADS)
Donker, H. C.; Katsnelson, M. I.; De Raedt, H.; Michielsen, K.
2016-09-01
The logical inference approach to quantum theory, proposed earlier De Raedt et al. (2014), is considered in a relativistic setting. It is shown that the Klein-Gordon equation for a massive, charged, and spinless particle derives from the combination of the requirements that the space-time data collected by probing the particle is obtained from the most robust experiment and that on average, the classical relativistic equation of motion of a particle holds.
NASA Astrophysics Data System (ADS)
Salazar-Ramírez, M.; Ojeda-Guillén, D.; Mota, R. D.
2016-09-01
We study a relativistic quantum particle in cosmic string spacetime in the presence of a magnetic field and a Coulomb-type scalar potential. It is shown that the radial part of this problem possesses the su(1 , 1) symmetry. We obtain the energy spectrum and eigenfunctions of this problem by using two algebraic methods: the Schrödinger factorization and the tilting transformation. Finally, we give the explicit form of the relativistic coherent states for this problem.
Weakly relativistic quantum kinetic theory for electrostatic wave modes in magnetized plasmas
Hussain, Azhar; Stefan, Martin; Brodin, Gert
2014-03-15
We have derived the electrostatic dispersion relation in a magnetized plasma using a recently developed quantum kinetic model based on the Dirac equation. The model contains weakly relativistic spin effects such as Thomas precession, the polarization currents associated with the spin and the spin-orbit coupling. It turns out that for strictly electrostatic perturbations the non-relativistic spin effects vanish, and the modification of the classical dispersion relation is solely associated with the relativistic terms. Several new wave modes appear due the electron spin effects, and an example for astrophysical plasmas are given.
Quantum resonances in reflection of relativistic electrons and positrons
NASA Astrophysics Data System (ADS)
Eykhorn, Yu. L.; Korotchenko, K. B.; Pivovarov, Yu. L.; Takabayashi, Y.
2015-07-01
Calculations based on the use of realistic potential of the system of crystallographic planes confirm earlier results on existence of resonances in reflection of relativistic electrons and positrons by the crystal surface, if the crystallographic planes are parallel to the surface.The physical reason of predicted phenomena, similar to the band structure of transverse energy levels, is connected with the Bloch form of the wave functions of electrons (positrons) near the crystallographic planes, which appears both in the case of planar channeling of relativistic electrons (positrons) and in reflection by a crystal surface. Calculations show that positions of maxima in reflection of relativistic electrons and positrons by crystal surface specifically depend on the angle of incidence with respect to the crystal surface and relativistic factor of electrons/positrons. These maxima form the Darwin tables similar to that in ultra-cold neutron diffraction.
Quantum Monte Carlo studies of relativistic effects in light nuclei
J. L. Forest; V. R. Pandharipande; A. Arriaga
1998-05-01
Relativistic Hamiltonians are defined as the sum of relativistic one-body kinetic energy, two- and three-body potentials and their boost corrections. In this work the authors use the variational Monte Carlo method to study two kinds of relativistic effects in the binding energy of {sup 3}H and {sup 4}He. The first is due to the nonlocalities in the relativistic kinetic energy and relativistic one-pion exchange potential (OPEP), and the second is from boost interaction. The OPEP contribution is reduced by about 15% by the relativistic nonlocality, which may also have significant effects on pion exchange currents. However, almost all of this reduction is canceled by changes in the kinetic energy and other interaction terms, and the total effect of the nonlocalities on the binding energy is very small. The boost interactions, on the other hand, give repulsive contributions of 0.4 (1.9) MeV in {sup 3}H ({sup 4}He) and account for 37% of the phenomenological part of the three-nucleon interaction needed in the nonrelativistic Hamiltonians.
Quantum-relativistic hydrodynamic model for a spin-polarized electron gas interacting with light.
Morandi, Omar; Zamanian, Jens; Manfredi, Giovanni; Hervieux, Paul-Antoine
2014-07-01
We develop a semirelativistic quantum fluid theory based on the expansion of the Dirac Hamiltonian to second order in 1/c. By making use of the Madelung representation of the wave function, we derive a set of hydrodynamic equations that comprises a continuity equation, an Euler equation for the mean velocity, and an evolution equation for the electron spin density. This hydrodynamic model is then applied to study the dynamics of a dense and weakly relativistic electron plasma. In particular, we investigate the impact of the quantum-relativistic spin effects on the Faraday rotation in a one-dimensional plasma slab irradiated by an x-ray laser source. PMID:25122397
NASA Astrophysics Data System (ADS)
Amoroso, Richard L.; Kauffman, Louis H.; Giandinoto, Salvatore
2013-09-01
We postulate bulk universal quantum computing (QC) cannot be achieved without surmounting the quantum uncertainty principle, an inherent barrier by empirical definition in the regime described by the Copenhagen interpretation of quantum theory - the last remaining hurdle to bulk QC. To surmount uncertainty with probability 1, we redefine the basis for the qubit utilizing a unique form of M-Theoretic Calabi-Yau mirror symmetry cast in an LSXD Dirac covariant polarized vacuum with an inherent `Feynman synchronization backbone'. This also incorporates a relativistic qubit (r-qubit) providing additional degrees of freedom beyond the traditional Block 2-sphere qubit bringing the r-qubit into correspondence with our version of Relativistic Topological Quantum Field Theory (RTQFT). We present a 3rd generation prototype design for simplifying bulk QC implementation.
Relativistic x-ray free-electron lasers in the quantum regime.
Eliasson, Bengt; Shukla, P K
2012-06-01
We present a nonlinear theory for relativistic x-ray free-electron lasers in the quantum regime, using a collective Klein-Gordon (KG) equation (for relativistic electrons), which is coupled with the Maxwell-Poisson equations for the electromagnetic and electrostatic fields. In our model, an intense electromagnetic wave is used as a wiggler which interacts with a relativistic electron beam to produce coherent tunable radiation. The KG-Maxwell-Poisson model is used to derive a general nonlinear dispersion relation for parametric instabilities in three space dimensions, including an arbitrarily large amplitude electromagnetic wiggler field. The nonlinear dispersion relation reveals the importance of quantum recoil effects and oblique scattering of the radiation that can be tuned by varying the beam energy. PMID:23005155
Exploring the propagation of relativistic quantum wavepackets in the trajectory-based formulation
NASA Astrophysics Data System (ADS)
Tsai, Hung-Ming; Poirier, Bill
2016-03-01
In the context of nonrelativistic quantum mechanics, Gaussian wavepacket solutions of the time-dependent Schrödinger equation provide useful physical insight. This is not the case for relativistic quantum mechanics, however, for which both the Klein-Gordon and Dirac wave equations result in strange and counterintuitive wavepacket behaviors, even for free-particle Gaussians. These behaviors include zitterbewegung and other interference effects. As a potential remedy, this paper explores a new trajectory-based formulation of quantum mechanics, in which the wavefunction plays no role [Phys. Rev. X, 4, 040002 (2014)]. Quantum states are represented as ensembles of trajectories, whose mutual interaction is the source of all quantum effects observed in nature—suggesting a “many interacting worlds” interpretation. It is shown that the relativistic generalization of the trajectory-based formulation results in well-behaved free-particle Gaussian wavepacket solutions. In particular, probability density is positive and well-localized everywhere, and its spatial integral is conserved over time—in any inertial frame. Finally, the ensemble-averaged wavepacket motion is along a straight line path through spacetime. In this manner, the pathologies of the wave-based relativistic quantum theory, as applied to wavepacket propagation, are avoided.
B. Julia-Diaz, H. Kamano, T.-S. H. Lee, A. Matsuyama, T. Sato, N. Suzuki
2009-04-01
Within the relativistic quantum field theory, we analyze the differences between the $\\pi N$ reaction models constructed from using (1) three-dimensional reductions of Bethe-Salpeter Equation, (2) method of unitary transformation, and (3) time-ordered perturbation theory. Their relations with the approach based on the dispersion relations of S-matrix theory are dicusssed.
Construction of relativistic quantum theory: a progress report
Noyes, H.P.
1986-06-01
We construct the particulate states of quantum physics using a recursive computer program that incorporates non-determinism by means of locally arbitrary choices. Quantum numbers and coupling constants arise from the construction via the unique 4-level combinatorial hierarchy. The construction defines indivisible quantum events with the requisite supraluminal correlations, yet does not allow supraluminal communication. Measurement criteria incorporate c, h-bar and m/sub p/ or (not ''and'') G, connected to laboratory events via finite particle number scattering theory and the counter paradigm. The resulting theory is discrete throughout, contains no infinities, and, as far as we have developed it, is in agreement with quantum mechanical and cosmological fact.
Relativistic quantum transport coefficients for second-order viscous hydrodynamics
NASA Astrophysics Data System (ADS)
Florkowski, Wojciech; Jaiswal, Amaresh; Maksymiuk, Ewa; Ryblewski, Radoslaw; Strickland, Michael
2015-05-01
We express the transport coefficients appearing in the second-order evolution equations for bulk viscous pressure and shear stress tensor using Bose-Einstein, Boltzmann, and Fermi-Dirac statistics for the equilibrium distribution function and Grad's 14-moment approximation as well as the method of Chapman-Enskog expansion for the nonequilibrium part. Focusing on the case of transversally homogeneous and boost-invariant longitudinal expansion of the viscous medium, we compare the results obtained using the above methods with those obtained from the exact solution of the massive 0+1 d relativistic Boltzmann equation in the relaxation-time approximation. We show that compared to the 14-moment approximation, the hydrodynamic transport coefficients obtained by employing the Chapman-Enskog method lead to better agreement with the exact solution of the relativistic Boltzmann equation.
Quantum-mechanical description of Lense-Thirring effect for relativistic scalar particles
NASA Astrophysics Data System (ADS)
Silenko, A. J.
2013-12-01
Exact expression for the Foldy-Wouthuysen Hamiltonian of scalar particles is used for a quantum-mechanical description of the relativistic Lense-Thirring effect. The exact evolution of the angular momentum operator in the Kerr field approximated by a spatially isotropic metric is found. The quantummechanical description of the full Lense-Thirring effect based on the Laplace-Runge-Lenz vector is given in the nonrelativistic and weak-field approximation. Relativistic quantum-mechanical equations for the velocity and acceleration operators are obtained. The equation for the acceleration defines the Coriolis-like and centrifugal-like accelerations and presents the quantum-mechanical description of the frame-dragging effect.
Weakly nonlinear ion-acoustic excitations in a relativistic model for dense quantum plasma.
Behery, E E; Haas, F; Kourakis, I
2016-02-01
The dynamics of linear and nonlinear ionic-scale electrostatic excitations propagating in a magnetized relativistic quantum plasma is studied. A quantum-hydrodynamic model is adopted and degenerate statistics for the electrons is taken into account. The dispersion properties of linear ion acoustic waves are examined in detail. A modified characteristic charge screening length and "sound speed" are introduced, for relativistic quantum plasmas. By employing the reductive perturbation technique, a Zakharov-Kuznetzov-type equation is derived. Using the small-k expansion method, the stability profile of weakly nonlinear slightly supersonic electrostatic pulses is also discussed. The effect of electron degeneracy on the basic characteristics of electrostatic excitations is investigated. The entire analysis is valid in a three-dimensional as well as in two-dimensional geometry. A brief discussion of possible applications in laboratory and space plasmas is included. PMID:26986431
Superpersistent currents and whispering gallery modes in relativistic quantum chaotic systems.
Xu, Hongya; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso
2015-01-01
Persistent currents (PCs), one of the most intriguing manifestations of the Aharonov-Bohm (AB) effect, are known to vanish for Schrödinger particles in the presence of random scatterings, e.g., due to classical chaos. But would this still be the case for Dirac fermions? Addressing this question is of significant value due to the tremendous recent interest in two-dimensional Dirac materials. We investigate relativistic quantum AB rings threaded by a magnetic flux and find that PCs are extremely robust. Even for highly asymmetric rings that host fully developed classical chaos, the amplitudes of PCs are of the same order of magnitude as those for integrable rings, henceforth the term superpersistent currents (SPCs). A striking finding is that the SPCs can be attributed to a robust type of relativistic quantum states, i.e., Dirac whispering gallery modes (WGMs) that carry large angular momenta and travel along the boundaries. We propose an experimental scheme using topological insulators to observe and characterize Dirac WGMs and SPCs, and speculate that these features can potentially be the base for a new class of relativistic qubit systems. Our discovery of WGMs in relativistic quantum systems is remarkable because, although WGMs are common in photonic systems, they are relatively rare in electronic systems. PMID:25758591
Superpersistent currents and whispering gallery modes in relativistic quantum chaotic systems
Xu, Hongya; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso
2015-01-01
Persistent currents (PCs), one of the most intriguing manifestations of the Aharonov-Bohm (AB) effect, are known to vanish for Schrödinger particles in the presence of random scatterings, e.g., due to classical chaos. But would this still be the case for Dirac fermions? Addressing this question is of significant value due to the tremendous recent interest in two-dimensional Dirac materials. We investigate relativistic quantum AB rings threaded by a magnetic flux and find that PCs are extremely robust. Even for highly asymmetric rings that host fully developed classical chaos, the amplitudes of PCs are of the same order of magnitude as those for integrable rings, henceforth the term superpersistent currents (SPCs). A striking finding is that the SPCs can be attributed to a robust type of relativistic quantum states, i.e., Dirac whispering gallery modes (WGMs) that carry large angular momenta and travel along the boundaries. We propose an experimental scheme using topological insulators to observe and characterize Dirac WGMs and SPCs, and speculate that these features can potentially be the base for a new class of relativistic qubit systems. Our discovery of WGMs in relativistic quantum systems is remarkable because, although WGMs are common in photonic systems, they are relatively rare in electronic systems. PMID:25758591
Dirac Equation and Quantum Relativistic Effects in a Single Trapped Ion
Lamata, L.; Leon, J.; Schaetz, T.; Solano, E.
2007-06-22
We present a method of simulating the Dirac equation in 3+1 dimensions for a free spin-1/2 particle in a single trapped ion. The Dirac bispinor is represented by four ionic internal states, and position and momentum of the Dirac particle are associated with the respective ionic variables. We show also how to simulate the simplified 1+1 case, requiring the manipulation of only two internal levels and one motional degree of freedom. Moreover, we study relevant quantum-relativistic effects, like the Zitterbewegung and Klein's paradox, the transition from massless to massive fermions, and the relativistic and nonrelativistic limits, via the tuning of controllable experimental parameters.
NASA Astrophysics Data System (ADS)
Choi, Taeseung
2015-03-01
A relativistic spin operator is the difference between the total and the orbital angular momentum. As the unique position operator for a localized state, the remarkable Newton-Wigner position operator, which has all the desirable commutation relations of a position operator, can give a proper spin operator. Historically, the three important spin operators proposed by Bogolubov et al., Pryce, and Foldy-Woutheysen, respectively were investigated to manifest a spin operator corresponding to the Newton-Wigner position operator. We clarify a unique spin operator in relativistic quantum mechanics, which can be described by using the Dirac Hamiltonian.
General relativistic effects in quantum interference of “clocks”
NASA Astrophysics Data System (ADS)
Zych, M.; Pikovski, I.; Costa, F.; Brukner, Č.
2016-06-01
Quantum mechanics and general relativity have been each successfully tested in numerous experiments. However, the regime where both theories are jointly required to explain physical phenomena remains untested by laboratory experiments, and is also not fully understood by theory. This contribution reviews recent ideas for a new type of experiments: quantum interference of “clocks”, which aim to test novel quantum effects that arise from time dilation. “Clock” interference experiments could be realised with atoms or photons in near future laboratory experiments.
Coherent radiation of relativistic electrons in dielectric fibers in the millimeter wavelength range
NASA Astrophysics Data System (ADS)
Naumenko, G. A.; Potylitsyn, A. P.; Bleko, V. V.; Soboleva, V. V.
2015-02-01
The generation of visible light by a relativistic electron beam in dielectric fibers was considered in X. Artru and C. Ray, Nucl. Inst. Meth. B 309, 4 (2013), where the characteristics of radiation induced in a fiber by the electromagnetic field of a relativistic charged particle were studied and it was emphasized that they differ from those in the traditional mechanisms of radiation such as transition and diffraction. We have experimentally studied the characteristics of such a radiation in the millimeter wavelength range. It has been shown that radiation can be generated through different mechanisms depending on the geometry of the position of a fiber with respect to the trajectory of the charged particle. Fibers have been shown to be promising for nondestructive diagnostics of accelerator beams.
Derivation of manifestly covariant quantum models for spinning relativistic particles
NASA Astrophysics Data System (ADS)
Marnelius, Robert; Mårtensson, Ulf
1990-05-01
A method to construct manifestly covariant models for relativistic spinning particles is given. The models involve manifestly covariant internal variables leading to discrete state spaces apart from the coordinate and momentum variables. The precise form of the models are extracted from the Bargmann-Wigner conditions on the Pauli-Lubanski operator, together with some consistency conditions. Several simple models are derived and analysed, some of which are new. Also manifestly conformally invariant models for particles with arbitrary spins are derived using a condition of Bracken and Jessup.
Quantum interferometric visibility as a witness of general relativistic proper time.
Zych, Magdalena; Costa, Fabio; Pikovski, Igor; Brukner, Časlav
2011-01-01
Current attempts to probe general relativistic effects in quantum mechanics focus on precision measurements of phase shifts in matter-wave interferometry. Yet, phase shifts can always be explained as arising because of an Aharonov-Bohm effect, where a particle in a flat space-time is subject to an effective potential. Here we propose a quantum effect that cannot be explained without the general relativistic notion of proper time. We consider interference of a 'clock'-a particle with evolving internal degrees of freedom-that will not only display a phase shift, but also reduce the visibility of the interference pattern. According to general relativity, proper time flows at different rates in different regions of space-time. Therefore, because of quantum complementarity, the visibility will drop to the extent to which the path information becomes available from reading out the proper time from the 'clock'. Such a gravitationally induced decoherence would provide the first test of the genuine general relativistic notion of proper time in quantum mechanics. PMID:22009037
Local thermodynamical equilibrium and the frame for a quantum relativistic fluid
NASA Astrophysics Data System (ADS)
Becattini, Francesco; Bucciantini, Leda; Grossi, Eduardo; Tinti, Leonardo
2015-05-01
We discuss the concept of local thermodynamical equilibrium in relativistic hydrodynamics in flat spacetime in a quantum statistical framework without an underlying kinetic description, suitable for strongly interacting fluids. We show that the appropriate definition of local equilibrium naturally leads to the introduction of a relativistic hydrodynamical frame in which the four-velocity vector is the one of a relativistic thermometer at equilibrium with the fluid, parallel to the inverse temperature four-vector , which then becomes a primary quantity. We show that this frame is the most appropriate for the expansion of the stress-energy tensor from local thermodynamical equilibrium and that therein the local laws of thermodynamics take on their simplest form. We discuss the difference between the frame and Landau frame and present an instance where they differ.
Parameter estimation using NOON states over a relativistic quantum channel
NASA Astrophysics Data System (ADS)
Hosler, Dominic; Kok, Pieter
2013-11-01
We study the effect of the acceleration of the observer on a parameter estimation protocol using NOON states. An inertial observer, Alice, prepares a NOON state in Unruh modes of the quantum field, and sends it to an accelerated observer, Rob. We calculate the quantum Fisher information of the state received by Rob. We find the counterintuitive result that the single-rail encoding outperforms the dual rail. The NOON states have an optimal N for the maximum information extractable by Rob, given his acceleration. This optimal N decreases with increasing acceleration.
Optical-lattice Hamiltonians for relativistic quantum electrodynamics
Kapit, Eliot; Mueller, Erich
2011-03-15
We show how interpenetrating optical lattices containing Bose-Fermi mixtures can be constructed to emulate the thermodynamics of quantum electrodynamics (QED). We present models of neutral atoms on lattices in 1+1, 2+1, and 3+1 dimensions whose low-energy effective action reduces to that of photons coupled to Dirac fermions of the corresponding dimensionality. We give special attention to (2+1)-dimensional quantum electrodynamics (QED3) and discuss how two of its most interesting features, chiral symmetry breaking and Chern-Simons physics, could be observed experimentally.
Ultrashort-Pulse Child-Langmuir Law in the Quantum and Relativistic Regimes
Ang, L. K.; Zhang, P.
2007-04-20
This Letter presents a consistent quantum and relativistic model of short-pulse Child-Langmuir (CL) law, of which the pulse length {tau} is less than the electron transit time in a gap of spacing D and voltage V. The classical value of the short-pulse CL law is enhanced by a large factor due to quantum effects when the pulse length and the size of the beam are, respectively, in femtosecond duration and nanometer scale. At high voltage larger than the electron rest mass, relativistic effects will suppress the enhancement of short-pulse CL law, which is confirmed by particle-in-cell simulation. When the pulse length is much shorter than the gap transit time, the current density is proportional to V, and to the inverse power of D and {tau}.
Scattering asymptotic conditions in Euclidean relativistic quantum theory
NASA Astrophysics Data System (ADS)
Aiello, Gordon J.; Polyzou, W. N.
2016-03-01
We discuss the formulation of the scattering asymptotic condition as a strong limit in Euclidean quantum theories satisfying the Osterwalder-Schrader axioms. When used with the invariance principle this provides a constructive method to compute scattering observables directly in the Euclidean formulation of the theory, without an explicit analytic continuation.
Geometric back-reaction in pre-inflation from relativistic quantum geometry
NASA Astrophysics Data System (ADS)
Arcodía, Marcos R. A.; Bellini, Mauricio
2016-06-01
The pre-inflationary evolution of the universe describes the beginning of the expansion from a static initial state, such that the Hubble parameter is initially zero, but increases to an asymptotic constant value, in which it could achieve a de Sitter (inflationary) expansion. The expansion is driven by a background phantom field. The back-reaction effects at this moment should describe vacuum geometrical excitations, which are studied in detail in this work using relativistic quantum geometry.
NASA Astrophysics Data System (ADS)
Di Rocco, Héctor O.; Lanzini, Fernando
2016-04-01
The correction to the Coulomb repulsion between two electrons due to the exchange of a transverse photon, referred to as the Breit interaction, as well as the main quantum electrodynamics contributions to the atomic energies (self-energy and vacuum polarization), are calculated using the recently formulated relativistic screened hydrogenic model. Comparison with the results of multiconfiguration Dirac-Hartree-Fock calculations and experimental X- ray energies is made.
NASA Astrophysics Data System (ADS)
Simulik, Volodimir
2016-01-01
The new relativistic equations of motion for the particles with arbitrary spin and nonzero mass have been introduced. The axiomatic level description of the relativistic canonical quantum mechanics of the arbitrary mass and spin has been given. The 64-dimensional ClR(0,6) algebra in terms of Dirac gamma matrices has been suggested. The link between the relativistic canonical quantum mechanics of the arbitrary spin and the covariant local field theory has been found. Different methods of the Dirac equation derivation have been reviewed. The manifestly covariant field equations for an arbitrary spin that follow from the quantum mechanical equations have been considered. The covariant local field theory equations for spin s = (1,1) particle-antiparticle doublet, spin s = (1,0,1,0) particle antiparticle multiplet, spin s = (3/2,3/2) particle-antiparticle doublet, spin s = (2,2) particle-antiparticle doublet, spin s = (2,0,2,0) particle-antiparticle multiplet and spin s = (2,1,2,1) particle-antiparticle multiplet have been introduced. The Maxwell-like equations for the boson with spin s = 1 and nonzero mass have been introduced as well.
Woesler, Richard
2007-02-21
The computations of the present text with non-relativistic quantum teleportation equations and special relativity are totally speculative, physically correct computations can be done using quantum field theory, which remain to be done in future. Proposals for what might be called statistical time loop experiments with, e.g., photon polarization states are described when assuming the simplified non-relativistic quantum teleportation equations and special relativity. However, a closed time loop would usually not occur due to phase incompatibilities of the quantum states. Histories with such phase incompatibilities are called inconsistent ones in the present text, and it is assumed that only consistent histories would occur. This is called an exclusion principle for inconsistent histories, and it would yield that probabilities for certain measurement results change. Extended multiple parallel experiments are proposed to use this statistically for transmission of classical information over distances, and regarding time. Experiments might be testable in near future. However, first a deeper analysis, including quantum field theory, remains to be done in future.
NASA Astrophysics Data System (ADS)
Gross, Franz; Stadler, Alfred
2010-09-01
We present the effective range expansions for the 1S0 and 3S1 scattering phase shifts, and the relativistic deuteron wave functions that accompany our recent high precision fits (with χ2/Ndata≃1) to the 2007 world np data below 350 MeV. The wave functions are expanded in a series of analytical functions (with the correct asymptotic behavior at both large and small arguments) that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A fortran subroutine to compute these wave functions can be obtained from the authors.
Franz Gross, Alfred Stadler
2010-09-01
We present the effective range expansions for the 1S0 and 3S1 scattering phase shifts, and the relativistic deuteron wave functions that accompany our recent high precision fits (with \\chi^2/N{data} \\simeq 1) to the 2007 world np data below 350 MeV. The wave functions are expanded in a series of analytical functions (with the correct asymptotic behavior at both large and small arguments) that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A fortran subroutine to compute these wave functions can be obtained from the authors.
Non-relativistic Gravity in Entropic Quantum Dynamics
Johnson, David T.; Caticha, Ariel
2011-03-14
Symmetries and transformations are explored in the framework of entropic quantum dynamics. This discussion leads to two conditions that are required for any transformation to qualify as a symmetry. The heart of this work lies in the application of these conditions to the extended Galilean transformation, which admits features of both special and general relativity. The effective gravitational potential representative of the strong equivalence principle arises naturally.
Inflationary back-reaction effects from Relativistic Quantum Geometry
NASA Astrophysics Data System (ADS)
Bellini, Mauricio
2016-03-01
We study the dynamics of scalar metric fluctuations in a non-perturbative variational formalism recently introduced, by which the dynamics of a geometrical scalar field θ, describes the quantum geometrical effects on a Weylian-like manifold with respect to a background Riemannian space-time. In this letter we have examined an example in the framework of inflationary cosmology. The resulting spectral predictions are in very good agreement with observations and other models of inflation.
Instantaneous spatially local projective measurements are consistent in a relativistic quantum field
Lin, Shih-Yuin
2012-12-15
Suppose the postulate of measurement in quantum mechanics can be extended to quantum field theory; then a local projective measurement at some moment on an object locally coupled with a relativistic quantum field will result in a projection or collapse of the wavefunctional of the combined system defined on the whole time-slice associated with the very moment of the measurement, if the relevant degrees of freedom have nonzero correlations. This implies that the wavefunctionals in the same Hamiltonian system but defined in different reference frames would collapse on different time-slices passing through the same local event where the measurement was done. Are these post-measurement states consistent with each other? We illustrate that the quantum states of the Raine-Sciama-Grove detector-field system started with the same initial Gaussian state defined on the same initial time-slice, then collapsed by the measurements on the pointlike detectors on different time-slices in different frames, will evolve to the same state of the combined system up to a coordinate transformation when compared on the same final time-slice. Such consistency is guaranteed by the spatial locality of interactions and the general covariance in a relativistic system, together with the spatial locality of measurements and the linearity of quantum dynamics in its quantum theory. - Highlights: Black-Right-Pointing-Pointer Spatially local quantum measurements in detector-field models are studied. Black-Right-Pointing-Pointer Local quantum measurement collapses the wavefunctional on the whole time-slice. Black-Right-Pointing-Pointer In different frames wavefunctionals of a field would collapse on different time-slices. Black-Right-Pointing-Pointer States collapsed by the same measurement will be consistent on the same final slice.
Thermodynamics of Quantum Gases for the Entire Range of Temperature
ERIC Educational Resources Information Center
Biswas, Shyamal; Jana, Debnarayan
2012-01-01
We have analytically explored the thermodynamics of free Bose and Fermi gases for the entire range of temperature, and have extended the same for harmonically trapped cases. We have obtained approximate chemical potentials for the quantum gases in closed forms of temperature so that the thermodynamic properties of the quantum gases become…
Cold atom simulation of interacting relativistic quantum field theories.
Cirac, J Ignacio; Maraner, Paolo; Pachos, Jiannis K
2010-11-01
We demonstrate that Dirac fermions self-interacting or coupled to dynamic scalar fields can emerge in the low energy sector of designed bosonic and fermionic cold atom systems. We illustrate this with two examples defined in two spacetime dimensions. The first one is the self-interacting Thirring model. The second one is a model of Dirac fermions coupled to a dynamic scalar field that gives rise to the Gross-Neveu model. The proposed cold atom experiments can be used to probe spectral or correlation properties of interacting quantum field theories thereby presenting an alternative to lattice gauge theory simulations. PMID:21231152
NASA Astrophysics Data System (ADS)
Thomas, Alec
2015-11-01
For certain classes of relativistic plasma problems, using a Lorentz boosted frame can be even more advantageous for gridded momentum space-position space-time simulations than Vay [Vay PRL 2007] showed was the case for position space-time simulations, resulting in speed up proportional to γboost6. The technique was applied using a Spectral Vlasov code to the problem of warm wavebreaking limits in relativistic plasma and demonstrates numerical results consistent with the analytic conclusions of Schroeder et al. [Schroeder PRE 2005]. By appropriate normalization, a self-similar behavior for the Vlasov equation in different Lorentz frames is found. These results are relevant to beam and laser driven plasma based accelerators and the potential for Vlasov simulation of them. National Science Foundation Career grant 1054164 and the Air Force Office of Scientific Research under Young Investigator Program grant FA9550-12-1-0310 and grant FA9550-14-1-0156.
Is Relativistic Quantum Mechanics Compatible with Special Relativity?
NASA Astrophysics Data System (ADS)
Lavenda, B. H.
2001-05-01
The transformation from a time-dependent random walk to quantum mechanics converts a modified Bessel function into an ordinary one together with a phase factor e,ir/2 for each time the electron flips both direction and handedness. Causality requires the argument to be greater than the order of the Bessel function. Assuming equal probabilities for jumps ± 1 , the normalized modified Bessel function of an imaginary argument is the solution of the finite difference differential Schrödinger equation whereas the same function of a real argument satisfies the diffusion equation. In the nonrelativistic limit, the stability condition of the difference scheme contains the mass whereas in the ultrarelativistic limit only the velocity of light appears. Particle waves in the nonrelativistic limit become elastic waves in the ultrarelativistic limit with a phase shift in the frequency and wave number of 7r/2. The ordinary Bessel function satisfies a second order recurrence relation which is a finite difference differential wave equation, using non-nearest neighbors, whose solutions are the chirality components of a free-particle in the zero fermion mass limit. Reintroducing the mass by a phase transformation transforms the wave equation into the Klein-Gordon equation but does not admit a solution in terms of ordinary Bessel functions. However, a sign change of the mass term permits a solution in terms of a modified Bessel function whose recurrence formulas produce all the results of special relativity. The Lorentz transformation maximizes the integral of the modified Bessel function and determines the paths of steepest descent in the classical limit. If the definitions of frequency and wave number in terms of the phase were used in special relativity, the condition that the frame be inertial would equate the superluminal phase velocity with the particle velocity in violation of causality. In order to get surfaces of constant phase to move at the group velocity, an
On a two-pass scheme without a faraday mirror for free-space relativistic quantum cryptography
Kravtsov, K. S.; Radchenko, I. V.; Korol'kov, A. V.; Kulik, S. P.; Molotkov, S. N.
2013-05-15
The stability of destructive interference independent of the input polarization and the state of a quantum communication channel in fiber optic systems used in quantum cryptography plays a principal role in providing the security of communicated keys. A novel optical scheme is proposed that can be used both in relativistic quantum cryptography for communicating keys in open space and for communicating them over fiber optic lines. The scheme ensures stability of destructive interference and admits simple automatic balancing of a fiber interferometer.
Quantum speed limit for a relativistic electron in a uniform magnetic field
NASA Astrophysics Data System (ADS)
Villamizar, D. V.; Duzzioni, E. I.
2015-10-01
We analyze the influence of relativistic effects on the minimum evolution time between two orthogonal states of a quantum system. Defining the initial state as a homogeneous superposition between two Hamiltonian eigenstates of an electron in a uniform magnetic field, we obtain a relation between the minimum evolution time and the displacement of the mean radial position of the electron wave packet. The quantum speed limit time is calculated for an electron dynamics described by Dirac and Schrödinger-Pauli equations considering different parameters, such as the strength of magnetic field and the linear momentum of the electron in the axial direction. We highlight that when the electron undergoes a region with extremely strong magnetic field the relativistic and nonrelativistic dynamics differ substantially, so that the description given by the Schrödinger-Pauli equation enables the electron to travel faster than c , which is prohibited by Einstein's theory of relativity. This approach allows a connection between the abstract Hilbert space and the space-time coordinates, besides the identification of the most appropriate quantum dynamics used to describe the electron motion.
Gross, Franz; Stadler, Alfred
2010-09-15
We present the effective range expansions for the {sup 1}S{sub 0} and {sup 3}S{sub 1} scattering phase shifts, and the relativistic deuteron wave functions that accompany our recent high precision fits (with {chi}{sup 2}/N{sub data{approx_equal}}1) to the 2007 world np data below 350 MeV. The wave functions are expanded in a series of analytical functions (with the correct asymptotic behavior at both large and small arguments) that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A fortran subroutine to compute these wave functions can be obtained from the authors.
Quench dynamics in long-range interacting quantum systems
NASA Astrophysics Data System (ADS)
Gong, Zhexuan
2016-05-01
A distinctive feature of atomic, molecular, and optical systems is that interactions between particles are often long-ranged. Control techniques from quantum optics often allow one to tune the pattern of these long-range interactions, creating an entirely new degree of freedom, absent in typical condensed matter systems. These tunable long-range interactions can result in very different far-from-equilibrium dynamics compared to systems with only short-range interactions. In the first half of the talk, I will describe how very general types of long-range interactions can qualitatively change the entanglement and correlation growth shortly after a quantum quench. In the second half of the talk I will show that, at longer times, long-range interactions can lead to exotic quasi-stationary states and dynamical phase transitions. These theoretical ideas have been explored in recent trapped-ion experiments, and connections to these experiments will be emphasized in both parts of the talk.
Generalized Lagrangian-Path Representation of Non-Relativistic Quantum Mechanics
NASA Astrophysics Data System (ADS)
Tessarotto, Massimo; Cremaschini, Claudio
2016-08-01
In this paper a new trajectory-based representation to non-relativistic quantum mechanics is formulated. This is ahieved by generalizing the notion of Lagrangian path (LP) which lies at the heart of the deBroglie-Bohm " pilot-wave" interpretation. In particular, it is shown that each LP can be replaced with a statistical ensemble formed by an infinite family of stochastic curves, referred to as generalized Lagrangian paths (GLP). This permits the introduction of a new parametric representation of the Schrödinger equation, denoted as GLP-parametrization, and of the associated quantum hydrodynamic equations. The remarkable aspect of the GLP approach presented here is that it realizes at the same time also a new solution method for the N-body Schrödinger equation. As an application, Gaussian-like particular solutions for the quantum probability density function (PDF) are considered, which are proved to be dynamically consistent. For them, the Schrödinger equation is reduced to a single Hamilton-Jacobi evolution equation. Particular solutions of this type are explicitly constructed, which include the case of free particles occurring in 1- or N-body quantum systems as well as the dynamics in the presence of suitable potential forces. In all these cases the initial Gaussian PDFs are shown to be free of the spreading behavior usually ascribed to quantum wave-packets, in that they exhibit the characteristic feature of remaining at all times spatially-localized.
Generalized Lagrangian-Path Representation of Non-Relativistic Quantum Mechanics
NASA Astrophysics Data System (ADS)
Tessarotto, Massimo; Cremaschini, Claudio
2016-02-01
In this paper a new trajectory-based representation to non-relativistic quantum mechanics is formulated. This is ahieved by generalizing the notion of Lagrangian path (LP) which lies at the heart of the deBroglie-Bohm " pilot-wave" interpretation. In particular, it is shown that each LP can be replaced with a statistical ensemble formed by an infinite family of stochastic curves, referred to as generalized Lagrangian paths (GLP). This permits the introduction of a new parametric representation of the Schrödinger equation, denoted as GLP-parametrization, and of the associated quantum hydrodynamic equations. The remarkable aspect of the GLP approach presented here is that it realizes at the same time also a new solution method for the N-body Schrödinger equation. As an application, Gaussian-like particular solutions for the quantum probability density function (PDF) are considered, which are proved to be dynamically consistent. For them, the Schrödinger equation is reduced to a single Hamilton-Jacobi evolution equation. Particular solutions of this type are explicitly constructed, which include the case of free particles occurring in 1- or N-body quantum systems as well as the dynamics in the presence of suitable potential forces. In all these cases the initial Gaussian PDFs are shown to be free of the spreading behavior usually ascribed to quantum wave-packets, in that they exhibit the characteristic feature of remaining at all times spatially-localized.
Long-Range Spin Transfer in Triple Quantum Dots
NASA Astrophysics Data System (ADS)
Sánchez, R.; Granger, G.; Gaudreau, L.; Kam, A.; Pioro-Ladrière, M.; Studenikin, S. A.; Zawadzki, P.; Sachrajda, A. S.; Platero, G.
2014-05-01
Tunneling in a quantum coherent structure is not restricted to only nearest neighbors. Hopping between distant sites is possible via the virtual occupation of otherwise avoided intermediate states. Here we report the observation of long-range transitions in the transport through three quantum dots coupled in series. A single electron is delocalized between the left and right quantum dots, while the center one remains always empty. Superpositions are formed, and both charge and spin are exchanged between the outermost dots. The delocalized electron acts as a quantum bus transferring the spin state from one end to the other. Spin selection is enabled by spin correlations. The process is detected via the observation of narrow resonances which are insensitive to Pauli spin blockade.
Long-range spin transfer in triple quantum dots.
Sánchez, R; Granger, G; Gaudreau, L; Kam, A; Pioro-Ladrière, M; Studenikin, S A; Zawadzki, P; Sachrajda, A S; Platero, G
2014-05-01
Tunneling in a quantum coherent structure is not restricted to only nearest neighbors. Hopping between distant sites is possible via the virtual occupation of otherwise avoided intermediate states. Here we report the observation of long-range transitions in the transport through three quantum dots coupled in series. A single electron is delocalized between the left and right quantum dots, while the center one remains always empty. Superpositions are formed, and both charge and spin are exchanged between the outermost dots. The delocalized electron acts as a quantum bus transferring the spin state from one end to the other. Spin selection is enabled by spin correlations. The process is detected via the observation of narrow resonances which are insensitive to Pauli spin blockade. PMID:24836266
Eigenenergies of a Relativistic Particle in an Infinite Range Linear Potential Using WKB Method
ERIC Educational Resources Information Center
Shivalingaswamy, T.; Kagali, B. A.
2011-01-01
Energy eigenvalues for a non-relativistic particle in a linear potential well are available. In this paper we obtain the eigenenergies for a relativistic spin less particle in a similar potential using an extension of the well-known WKB method treating the potential as the time component of a four-vector potential. Since genuine bound states do…
Thermodynamics in the vicinity of a relativistic quantum critical point in 2+1 dimensions.
Rançon, A; Kodio, O; Dupuis, N; Lecheminant, P
2013-07-01
We study the thermodynamics of the relativistic quantum O(N) model in two space dimensions. In the vicinity of the zero-temperature quantum critical point (QCP), the pressure can be written in the scaling form P(T)=P(0)+N(T(3)/c(2))F(N)(Δ/T), where c is the velocity of the excitations at the QCP and |Δ| a characteristic zero-temperature energy scale. Using both a large-N approach to leading order and the nonperturbative renormalization group, we compute the universal scaling function F(N). For small values of N (Nquantum critical regime (|x|quantum disordered (x>/~1) regimes, but fails to describe the nonmonotonic behavior of F(N) in the quantum critical regime. We discuss the renormalization-group flows in the various regimes near the QCP and make the connection with the quantum nonlinear sigma model in the renormalized classical regime. We compute the Berezinskii-Kosterlitz-Thouless transition temperature in the quantum O(2) model and find that in the vicinity of the QCP the universal ratio T(BKT)/ρ(s)(0) is very close to π/2, implying that the stiffness ρ(s)(T(BKT)(-)) at the transition is only slightly reduced with respect to the zero-temperature stiffness ρ(s)(0). Finally, we briefly discuss the experimental determination of the universal function F(2) from the pressure of a Bose gas in an optical lattice near the superfluid-Mott-insulator transition. PMID:23944420
Non-relativistic Limit of Dirac Equations in Gravitational Field and Quantum Effects of Gravity
NASA Astrophysics Data System (ADS)
Wu, Ning
2006-03-01
Based on unified theory of electromagnetic interactions and gravitational interactions, the non-relativistic limit of the equation of motion of a charged Dirac particle in gravitational field is studied. From the Schrödinger equation obtained from this non-relativistic limit, we can see that the classical Newtonian gravitational potential appears as a part of the potential in the Schrödinger equation, which can explain the gravitational phase effects found in COW experiments. And because of this Newtonian gravitational potential, a quantum particle in the earth's gravitational field may form a gravitationally bound quantized state, which has already been detected in experiments. Three different kinds of phase effects related to gravitational interactions are studied in this paper, and these phase effects should be observable in some astrophysical processes. Besides, there exists direct coupling between gravitomagnetic field and quantum spin, and radiation caused by this coupling can be used to directly determine the gravitomagnetic field on the surface of a star.
Li, Wei-Li; Su, Jing; Jian, Tian; Lopez, Gary V; Hu, Han-Shi; Cao, Guo-Jin; Li, Jun; Wang, Lai-Sheng
2014-03-01
The electronic structures of actinide systems are extremely complicated and pose considerable challenges both experimentally and theoretically because of significant electron correlation and relativistic effects. Here we report an investigation of the electronic structure and chemical bonding of uranium dioxides, UO2(-) and UO2, using photoelectron spectroscopy and relativistic quantum chemistry. The electron affinity of UO2 is measured to be 1.159(20) eV. Intense detachment bands are observed from the UO2(-) low-lying (7sσg)(2)(5fϕu)(1) orbitals and the more deeply bound O2p-based molecular orbitals which are separated by a large energy gap from the U-based orbitals. Surprisingly, numerous weak photodetachment transitions are observed in the gap region due to extensive two-electron transitions, suggesting strong electron correlations among the (7sσg)(2)(5fϕu)(1) electrons in UO2(-) and the (7sσg)(1)(5fϕu)(1) electrons in UO2. These observations are interpreted using multi-reference ab initio calculations with inclusion of spin-orbit coupling. The strong electron correlations and spin-orbit couplings generate orders-of-magnitude more detachment transitions from UO2(-) than expected on the basis of the Koopmans' theorem. The current experimental data on UO2(-) provide a long-sought opportunity to arbitrating various relativistic quantum chemistry methods aimed at handling systems with strong electron correlations. PMID:24606360
Notes on Translational and Rotational Properties of Tensor Fields in Relativistic Quantum Mechanics
NASA Astrophysics Data System (ADS)
Dvoeglazov, V. V.
Recently, several discussions on the possible observability of 4-vector fields have been published in literature. Furthermore, several authors recently claimed existence of the helicity=0 fundamental field. We re-examine the theory of antisymmetric tensor fields and 4-vector potentials. We study the massless limits. In fact, a theoretical motivation for this venture is the old papers of Ogievetskiĭ and Polubarinov, Hayashi, and Kalb and Ramond. Ogievetskiĭ and Polubarinov proposed the concept of the notoph, whose helicity properties are complementary to those of the photon. We analyze the quantum field theory with taking into account mass dimensions of the notoph and the photon. It appears to be possible to describe both photon and notoph degrees of freedom on the basis of the modified Bargmann-Wigner formalism for the symmetric second-rank spinor. Next, we proceed to derive equations for the symmetric tensor of the second rank on the basis of the Bargmann-Wigner formalism in a straightforward way. The symmetric multispinor of the fourth rank is used. Due to serious problems with the interpretation of the results obtained on using the standard procedure we generalize it and obtain the spin-2 relativistic equations, which are consistent with the general relativity. Thus, in fact we deduced the gravitational field equations from relativistic quantum mechanics. The relations of this theory with the scalar-tensor theories of gravitation and f(R) are discussed. Particular attention has been paid to the correct definitions of the energy-momentum tensor and other Nöther currents in the electromagnetic theory, the relativistic theory of gravitation, the general relativity, and their generalizations. We estimate possible interactions, fermion-notoph, graviton-notoph, photon-notoph, and we conclude that they can probably be seen in experiments in the next few years.
Kent, Adrian; Munro, William J.; Spiller, Timothy P.
2011-07-15
We define the task of quantum tagging, that is, authenticating the classical location of a classical tagging device by sending and receiving quantum signals from suitably located distant sites, in an environment controlled by an adversary whose quantum information processing and transmitting power is unbounded. We define simple security models for this task and briefly discuss alternatives. We illustrate the pitfalls of naive quantum cryptographic reasoning in this context by describing several protocols which at first sight appear unconditionally secure but which, as we show, can in fact be broken by teleportation-based attacks. We also describe some protocols which cannot be broken by these specific attacks, but do not prove they are unconditionally secure. We review the history of quantum tagging protocols, and show that protocols previously proposed by Malaney and Chandran et al. are provably insecure.
A statistical model for relativistic quantum fluids interacting with an intense electromagnetic wave
NASA Astrophysics Data System (ADS)
Mahajan, Swadesh M.; Asenjo, Felipe A.
2016-05-01
A statistical model for relativistic quantum fluids interacting with an arbitrary amplitude circularly polarized electromagnetic wave is developed in two steps. First, the energy spectrum and the wave function for a quantum particle (Klein Gordon and Dirac) embedded in the electromagnetic wave are calculated by solving the appropriate eigenvalue problem. The energy spectrum is anisotropic in the momentum K and reflects the electromagnetic field through the renormalization of the rest mass m to M =√{m2+q2A2 } . Based on this energy spectrum of this quantum particle plus field combination (QPF), a statistical mechanics model of the quantum fluid made up of these weakly interacting QPF is developed. Preliminary investigations of the formalism yield highly interesting results—a new scale for temperature, and fundamental modification of the dispersion relation of the electromagnetic wave. It is expected that this formulation could, inter alia, uniquely advance our understanding of laboratory as well as astrophysical systems where one encounters arbitrarily large electromagnetic fields.
NASA Astrophysics Data System (ADS)
Ogawa, Tatsuhiko; Sato, Tatsuhiko; Hashimoto, Shintaro; Niita, Koji
2016-05-01
To predict angular distribution of fragments produced in nucleusnucleus collisions, JAERI quantum molecular dynamics model (JQMD) was improved. Because JQMD underestimated fragments in the forward angle, which were mainly produced by peripheral collisions, JQMD was revised so as to simulate peripheral collisions accurately. Density-dependent in-medium effect and relativistic effect on nucleonnucleon interactions were incorporated for this purpose. The revised version of JQMD coupled with a statistical decay model was used to calculate differential fragment production cross sections measured in earlier studies. Comparison of the measured data and calculation by the revised and old JQMD showed that the revised JQMD can predict fragment angular distribution better than old JQMD. Particularly, agreement of fragment yield in the forward angle is substantially improved.
Quantum-electrodynamical birefringence vanishing in a thermal relativistic pair plasma.
Huang, Y S
2015-01-01
Quantum electrodynamical (QED) birefringence in a thermal relativistic pair plasma with the presence of the strong crossed field: E0 ⊥ B0, is proposed and investigated. We clarify the coupling relationship and competition between the QED effect and the plasma collective effect and find the critical condition that makes the birefringence vanish. In a relative weak electromagnetic field, the birefringence is dominated by the coupling of the QED-effect, the collective effect and the E0 × B0 drift effect. In a relative strong electromagnetic field, we obtain the formulations stating the competition between the QED effect and the collective effect and then the critical conditions so that they are canceled with each other and the birefringence vanishes. With our results, a new possible scheme is proposed to estimate the thickness of the magnetosphere in a millisecond pulsar and the plasma density of a pulsar, if the magnetic field is known beforehand. PMID:26522493
Quantum-electrodynamical birefringence vanishing in a thermal relativistic pair plasma
Huang, Y. S.
2015-01-01
Quantum electrodynamical (QED) birefringence in a thermal relativistic pair plasma with the presence of the strong crossed field: , is proposed and investigated. We clarify the coupling relationship and competition between the QED effect and the plasma collective effect and find the critical condition that makes the birefringence vanish. In a relative weak electromagnetic field, the birefringence is dominated by the coupling of the QED-effect, the collective effect and the drift effect. In a relative strong electromagnetic field, we obtain the formulations stating the competition between the QED effect and the collective effect and then the critical conditions so that they are canceled with each other and the birefringence vanishes. With our results, a new possible scheme is proposed to estimate the thickness of the magnetosphere in a millisecond pulsar and the plasma density of a pulsar, if the magnetic field is known beforehand. PMID:26522493
Fractional quantum mechanics on networks: Long-range dynamics and quantum transport.
Riascos, A P; Mateos, José L
2015-11-01
In this paper we study the quantum transport on networks with a temporal evolution governed by the fractional Schrödinger equation. We generalize the dynamics based on continuous-time quantum walks, with transitions to nearest neighbors on the network, to the fractional case that allows long-range displacements. By using the fractional Laplacian matrix of a network, we establish a formalism that combines a long-range dynamics with the quantum superposition of states; this general approach applies to any type of connected undirected networks, including regular, random, and complex networks, and can be implemented from the spectral properties of the Laplacian matrix. We study the fractional dynamics and its capacity to explore the network by means of the transition probability, the average probability of return, and global quantities that characterize the efficiency of this quantum process. As a particular case, we explore analytically these quantities for circulant networks such as rings, interacting cycles, and complete graphs. PMID:26651751
Fractional quantum mechanics on networks: Long-range dynamics and quantum transport
NASA Astrophysics Data System (ADS)
Riascos, A. P.; Mateos, José L.
2015-11-01
In this paper we study the quantum transport on networks with a temporal evolution governed by the fractional Schrödinger equation. We generalize the dynamics based on continuous-time quantum walks, with transitions to nearest neighbors on the network, to the fractional case that allows long-range displacements. By using the fractional Laplacian matrix of a network, we establish a formalism that combines a long-range dynamics with the quantum superposition of states; this general approach applies to any type of connected undirected networks, including regular, random, and complex networks, and can be implemented from the spectral properties of the Laplacian matrix. We study the fractional dynamics and its capacity to explore the network by means of the transition probability, the average probability of return, and global quantities that characterize the efficiency of this quantum process. As a particular case, we explore analytically these quantities for circulant networks such as rings, interacting cycles, and complete graphs.
NASA Astrophysics Data System (ADS)
Horwitz, Lawrence; Hu, Bei-Lok; Lee, Da-Shin; Gill, Tepper; Land, Martin
2011-12-01
Although the subject of relativistic dynamics has been explored from both classical and quantum mechanical points of view since the work of Einstein and Dirac, its most striking development has been in the framework of quantum field theory. The very accurate calculations of spectral and scattering properties, for example, of the anamolous magnetic moment of the electron and the Lamb shift in quantum electrodynamics, and many qualitative features of the strong and electroweak interactions, demonstrate the very great power of description achieved in this framework. Yet, many fundamental questions remain to be clarified, such as the structure of classical realtivistic dynamical theories on the level of Hamilton and Lagrange in Minkowski space as well as on the curved manifolds of general relativity. There moreover remains the important question of the covariant classical description of systems at high energy for which particle production effects are not large, such as discussed in Synge's book, The Relativistic Gas, and in Balescu's book on relativistic statistical mechanics. In recent years, the study of high energy plasmas and heavy ion collisions has emphasized the importance of developing the techniques of relativistic mechanics. The results of Linder et al (Phys. Rev. Lett. 95 0040401 (2005)) as well as the more recent work of Palacios et al (Phys. Rev. Lett. 103 253001 (2009)) and others, have shown that there must be a quantum theory with coherence in time. Such a theory, manifestly covariant under the transformations of special relativity with an invariant evolution parameter, such as that of Stueckelberg (Helv. Phys. Acta 14 322, 588 (1941); 15 23 (1942); see also R P Feynman Phys. Rev. 80 4401 and J S Schwinger Phys. Rev. 82 664 (1951)) could provide a suitable basis for the study of such questions, as well as many others for which the application of the standard methods of quantum field theory are difficult to manage, involving, in particular, local
Robust Multiple-Range Coherent Quantum State Transfer.
Chen, Bing; Peng, Yan-Dong; Li, Yong; Qian, Xiao-Feng
2016-01-01
We propose a multiple-range quantum communication channel to realize coherent two-way quantum state transport with high fidelity. In our scheme, an information carrier (a qubit) and its remote partner are both adiabatically coupled to the same data bus, i.e., an N-site tight-binding chain that has a single defect at the center. At the weak interaction regime, our system is effectively equivalent to a three level system of which a coherent superposition of the two carrier states constitutes a dark state. The adiabatic coupling allows a well controllable information exchange timing via the dark state between the two carriers. Numerical results show that our scheme is robust and efficient under practically inevitable perturbative defects of the data bus as well as environmental dephasing noise. PMID:27364891
Robust Multiple-Range Coherent Quantum State Transfer
Chen, Bing; Peng, Yan-Dong; Li, Yong; Qian, Xiao-Feng
2016-01-01
We propose a multiple-range quantum communication channel to realize coherent two-way quantum state transport with high fidelity. In our scheme, an information carrier (a qubit) and its remote partner are both adiabatically coupled to the same data bus, i.e., an N-site tight-binding chain that has a single defect at the center. At the weak interaction regime, our system is effectively equivalent to a three level system of which a coherent superposition of the two carrier states constitutes a dark state. The adiabatic coupling allows a well controllable information exchange timing via the dark state between the two carriers. Numerical results show that our scheme is robust and efficient under practically inevitable perturbative defects of the data bus as well as environmental dephasing noise. PMID:27364891
Robust Multiple-Range Coherent Quantum State Transfer
NASA Astrophysics Data System (ADS)
Chen, Bing; Peng, Yan-Dong; Li, Yong; Qian, Xiao-Feng
2016-07-01
We propose a multiple-range quantum communication channel to realize coherent two-way quantum state transport with high fidelity. In our scheme, an information carrier (a qubit) and its remote partner are both adiabatically coupled to the same data bus, i.e., an N-site tight-binding chain that has a single defect at the center. At the weak interaction regime, our system is effectively equivalent to a three level system of which a coherent superposition of the two carrier states constitutes a dark state. The adiabatic coupling allows a well controllable information exchange timing via the dark state between the two carriers. Numerical results show that our scheme is robust and efficient under practically inevitable perturbative defects of the data bus as well as environmental dephasing noise.
Five-dimensional Hamiltonian-Jacobi approach to relativistic quantum mechanics
Rose, Harald
2003-12-11
A novel theory is outlined for describing the dynamics of relativistic electrons and positrons. By introducing the Lorentz-invariant universal time as a fifth independent variable, the Hamilton-Jacobi formalism of classical mechanics is extended from three to four spatial dimensions. This approach allows one to incorporate gravitation and spin interactions in the extended five-dimensional Lagrangian in a covariant form. The universal time has the function of a hidden Bell parameter. By employing the method of variation with respect to the four coordinates of the particle and the components of the electromagnetic field, the path equation and the electromagnetic field produced by the charge and the spin of the moving particle are derived. In addition the covariant equations for the dynamics of the components of the spin tensor are obtained. These equations can be transformed to the familiar BMT equation in the case of homogeneous electromagnetic fields. The quantization of the five-dimensional Hamilton-Jacobi equation yields a five-dimensional spinor wave equation, which degenerates to the Dirac equation in the stationary case if we neglect gravitation. The quantity which corresponds to the probability density of standard quantum mechanics is the four-dimensional mass density which has a real physical meaning. By means of the Green method the wave equation is transformed into an integral equation enabling a covariant relativistic path integral formulation. Using this approach a very accurate approximation for the four-dimensional propagator is derived. The proposed formalism makes Dirac's hole theory obsolete and can readily be extended to many particles.
Long range correlations and the soft ridge in relativistic nuclear collisions
Gavin, Sean; Moschelli, George; McLerran, Larry
2009-05-15
Relativistic Heavy Ion Collider experiments exhibit correlations peaked in relative azimuthal angle and extended in rapidity. Called the ridge, this peak occurs both with and without a jet trigger. We argue that the untriggered ridge arises when particles formed by flux tubes in an early Glasma stage later manifest transverse flow. Combining a blast wave model of flow fixed by single-particle spectra with a simple description of the Glasma, we find excellent agreement with current data.
Quantum Defect Theory for Long-range Anisotropic Interactions
NASA Astrophysics Data System (ADS)
Ruzic, Brandon P.; Bohn, John L.; Greene, Chris H.
2014-05-01
Quantum Defect Theory (QDT) is a numerically efficient and accurate tool for studying a wide variety of ultracold atomic collisions, where the asymptotic behavior of the atoms is well described by a set of simple parameters. However, analytic formulas for these parameters only exist for the pure - 1 /R6 potential. The long-range parameters are given by simple power law equations in the collision energy, and the bound state energies of different partial waves are simply related. We extend these formulas to encompass all potentials of the form - 1 /Rn , where n > 2 . Moreover, the accuracy of QDT is limited by long-range anisotropic interactions, which, for example, play an important role in collisions of dysprosium or erbium atoms. We present our recent developments on numerically treating this type of interaction within perturbation theory. This work is supported by the US Department of Energy.
Quantum control and long-range quantum correlations in dynamical Casimir arrays
NASA Astrophysics Data System (ADS)
Stassi, Roberto; De Liberato, Simone; Garziano, Luigi; Spagnolo, Bernardo; Savasta, Salvatore
2015-07-01
The recent observation of the dynamical Casimir effect in a modulated superconducting waveguide, culminating thirty years of worldwide research, empowered the quantum technology community with a tool to create entangled photons on chip. In this work we show how, going beyond the single waveguide paradigm using a scalable array, it is possible to create multipartite nonclassical states, with the possibility to control the long-range quantum correlations of the emitted photons. In particular, our finite-temperature theory shows how maximally entangled NOON states can be engineered in a realistic setup. The results presented here open the way to new kinds of quantum fluids of light, arising from modulated vacuum fluctuations in linear systems.
Quantum radiation reaction force on a one-dimensional cavity with two relativistic moving mirrors
NASA Astrophysics Data System (ADS)
Alves, Danilo T.; Granhen, Edney R.; Pires, Wagner P.
2010-08-01
We consider a real massless scalar field inside a cavity with two moving mirrors in a two-dimensional spacetime, satisfying the Dirichlet boundary condition at the instantaneous position of the boundaries, for arbitrary and relativistic laws of motion. Considering vacuum as the initial field state, we obtain formulas for the exact value of the energy density of the field and the quantum force acting on the boundaries, which extend results found in previous papers [D. T. Alves, E. R. Granhen, H. O. Silva, and M. G. Lima, Phys. Rev. DPRVDAQ1550-7998 81, 025016 (2010); 10.1103/PhysRevD.81.025016L. Li and B.-Z. Li, Phys. Lett. APYLAAG0375-9601 300, 27 (2002); 10.1016/S0375-9601(02)00674-6L. Li and B.-Z. Li, Chin. Phys. Lett.CPLEEU0256-307X 19, 1061 (2002); 10.1088/0256-307X/19/8/310L. Li and B.-Z. Li, Acta Phys. Sin.WLHPAR1000-3290 52, 2762 (2003); C. K. Cole and W. C. Schieve, Phys. Rev. A 64, 023813 (2001)PLRAAN1050-294710.1103/PhysRevA.64.023813]. For the particular cases of a cavity with just one moving boundary, nonrelativistic velocities, or in the limit of infinity length of the cavity (a single mirror), our results coincide with those found in the literature.
Quantum radiation reaction force on a one-dimensional cavity with two relativistic moving mirrors
Alves, Danilo T.; Granhen, Edney R.; Pires, Wagner P.
2010-08-15
We consider a real massless scalar field inside a cavity with two moving mirrors in a two-dimensional spacetime, satisfying the Dirichlet boundary condition at the instantaneous position of the boundaries, for arbitrary and relativistic laws of motion. Considering vacuum as the initial field state, we obtain formulas for the exact value of the energy density of the field and the quantum force acting on the boundaries, which extend results found in previous papers [D. T. Alves, E. R. Granhen, H. O. Silva, and M. G. Lima, Phys. Rev. D 81, 025016 (2010); L. Li and B.-Z. Li, Phys. Lett. A 300, 27 (2002); L. Li and B.-Z. Li, Chin. Phys. Lett. 19, 1061 (2002); L. Li and B.-Z. Li, Acta Phys. Sin. 52, 2762 (2003); C. K. Cole and W. C. Schieve, Phys. Rev. A 64, 023813 (2001)]. For the particular cases of a cavity with just one moving boundary, nonrelativistic velocities, or in the limit of infinity length of the cavity (a single mirror), our results coincide with those found in the literature.
Non-relativistic matter and dark energy in a quantum conformal model
NASA Astrophysics Data System (ADS)
Kashyap, Gopal; Jain, Pankaj; Mitra, Subhadip
2016-02-01
We consider a generalization of the Standard Model whose action displays conformal invariance in d dimensions. The model contains a strongly coupled dark matter sector which breaks conformal symmetry dynamically. The model evades conformal anomaly and leads to identically zero vacuum energy in flat space-time. Hence it does not suffer from the problem of fine tuning of the cosmological constant. We determine the contribution of non-relativistic matter to the energy-momentum tensor and determine a parameter regime in which it approximately reduces to the standard result. We show how dark energy and dark matter arises in this model. We discuss the parameter range for which the model reduces to the ΛCDM model and hence is consistent with observations.
Aquino, Fredy W.; Govind, Niranjan; Autschbach, Jochen
2011-10-01
Density functional theory (DFT) calculations of NMR chemical shifts and molecular g-tensors with Gaussian-type orbitals are implemented via second-order energy derivatives within the scalar relativistic zeroth order regular approximation (ZORA) framework. Nonhybrid functionals, standard (global) hybrids, and range-separated (Coulomb-attenuated, long-range corrected) hybrid functionals are tested. Origin invariance of the results is ensured by use of gauge-including atomic orbital (GIAO) basis functions. The new implementation in the NWChem quantum chemistry package is verified by calculations of nuclear shielding constants for the heavy atoms in HX (X=F, Cl, Br, I, At) and H2X (X = O, S, Se, Te, Po), and Te chemical shifts in a number of tellurium compounds. The basis set and functional dependence of g-shifts is investigated for 14 radicals with light and heavy atoms. The problem of accurately predicting F NMR shielding in UF6-nCln, n = 1 to 6, is revisited. The results are sensitive to approximations in the density functionals, indicating a delicate balance of DFT self-interaction vs. correlation. For the uranium halides, the results with the range-separated functionals are mixed.
NASA Astrophysics Data System (ADS)
Horwitz, L. P.; Land, Martin C.; Gill, Tepper; Lusanna, Luca; Salucci, Paolo
2013-04-01
Although the subject of relativistic dynamics has been explored, from both classical and quantum mechanical points of view, since the work of Einstein and Dirac, its most striking development has been in the framework of quantum field theory. The very accurate calculations of spectral and scattering properties, for example, of the anomalous magnetic moment of the electron and the Lamb shift in quantum electrodynamics, and many qualitative features of the strong and electroweak interactions, demonstrate the very great power of description achieved in this framework. Yet, many fundamental questions remain to be clarified, such as the structure of classical relativistic dynamical theories on the level of Hamilton and Lagrange in Minkowski space as well as on the curved manifolds of general relativity. There moreover remains the important question of the covariant classical description of systems at high energy for which particle production effects are not large, such as discussed in Synge's book, The Relativistic Gas, and in Balescu's book on relativistic statistical mechanics. In recent years, the study of high energy plasmas and heavy ion collisions has emphasized the importance of developing the techniques of relativistic mechanics. The results of Lindner et al [Physical Review Letters 95 0040401 (2005)] as well as the more recent proposal of Palacios et al [Phys. Rev. Lett. 103 253001 (2009)] and others, have shown that there must be a quantum theory with coherence in time. Such a theory, manifestly covariant under the transformations of special relativity with an invariant evolution parameter, such as that of Stueckelberg [Helv. Phys. Acta 14 322, 588 (1941); 15 23 (1942); see also R P Feynman Phys. Rev. 80 4401 and J S Schwinger Phys. Rev. 82 664 (1951)] could provide a suitable basis for the study of such questions, as well as many others for which the application of the standard methods of quantum field theory are difficult to manage, involving, in particular
NASA Astrophysics Data System (ADS)
Bakke, K.; Belich, H.
2015-11-01
We discuss the appearance of geometric quantum phases for a Dirac neutral particle in the context of relativistic quantum mechanics based on possible scenarios of the Lorentz symmetry violation tensor background in the CPT-even gauge sector of Standard Model Extension. We assume that the Lorentz symmetry breaking is determined by a tensor background given by (KF)μναβ, then, relativistic analogues of the Anandan quantum phase [J. Anandan, Phys. Lett. A 138, 347 (1989)] are obtained based on the parity-even and parity-odd sectors of the tensor (KF)μναβ.
Use of the Lorentz-operator in relativistic quantum mechanics to guarentee a single-energy root
Ritchie, A B
1998-08-01
The Lorentz-operator form of relativistic quantum mechanics, with relativistic wave equation i{h_bar}{partial_derivative}{psi}/{partial_derivative}t=(mc{sup 2}{gamma}+e{Phi}){psi}, is implemented to guarantee a single-energy root. The Lorentz factor as modified by Pauli's ansatz is given by {gamma}={radical}1+[{rvec {sigma}}{center_dot}(i{h_bar}{rvec {del}}+(e/c){rvec A})]{sup 2}/m{sup 2}c{sup 2}, such that the theory is appropriate for electrons. Magnetic fine structure in the Lorentz relativistic wave equation emerges on the use of an appropriate operator form of the Lienard-Wiechert four- potential ({Phi},{rvec A}) from electromagnetic theory. Although computationally more intensive the advantage of the theory is the elimination of the negative-root of the energy and an interpretation of the wave function based on a one-particle, positive definite probability density like that of nonrelativistic quantum mechanics.
Patil, S. D.; Takale, M. V.
2014-06-15
Habibi and Ghamari have presented a Comment on our paper [Phys. Plasmas 20, 072703 (2013)] by examining quantum dielectric response in thermal quantum plasma. They have modeled the relativistic self-focusing of Gaussian laser beam in cold and warm quantum plasmas and reported that self-focusing length does not change in both situations. In this response, we have reached the following important conclusions about the comment itself.
Entanglement Entropy in Quantum Spin Chains with Finite Range Interaction
NASA Astrophysics Data System (ADS)
Its, A. R.; Mezzadri, F.; Mo, M. Y.
2008-11-01
We study the entropy of entanglement of the ground state in a wide family of one-dimensional quantum spin chains whose interaction is of finite range and translation invariant. Such systems can be thought of as generalizations of the XY model. The chain is divided in two parts: one containing the first consecutive L spins; the second the remaining ones. In this setting the entropy of entanglement is the von Neumann entropy of either part. At the core of our computation is the explicit evaluation of the leading order term as L → ∞ of the determinant of a block-Toeplitz matrix with symbol Φ(z) = left(begin{array}{cc} iλ & g(z) \\ g^{-1}(z) & i λ right), where g( z) is the square root of a rational function and g(1/ z) = g -1( z). The asymptotics of such determinant is computed in terms of multi-dimensional theta-functions associated to a hyperelliptic curve {mathcal{L}} of genus g ≥ 1, which enter into the solution of a Riemann-Hilbert problem. Phase transitions for these systems are characterized by the branch points of {mathcal{L}} approaching the unit circle. In these circumstances the entropy diverges logarithmically. We also recover, as particular cases, the formulae for the entropy discovered by Jin and Korepin [14] for the XX model and Its, Jin and Korepin [12, 13] for the XY model.
Quantum spin models with long-range interactions and tunnelings: a quantum Monte Carlo study
NASA Astrophysics Data System (ADS)
Maik, Michał; Hauke, Philipp; Dutta, Omjyoti; Zakrzewski, Jakub; Lewenstein, Maciej
2012-11-01
We use a quantum Monte Carlo method to investigate various classes of two-dimensional spin models with long-range interactions at low temperatures. In particular, we study a dipolar XXZ model with U(1) symmetry that appears as a hard-core boson limit of an extended Hubbard model describing polarized dipolar atoms or molecules in an optical lattice. Tunneling, in such a model, is short-range, whereas density-density couplings decay with distance following a cubic power law. We also investigate an XXZ model with long-range couplings of all three spin components—such a model describes a system of ultracold ions in a lattice of microtraps. We describe an approximate phase diagram for such systems at zero and at finite temperature, and compare their properties. In particular, we compare the extent of crystalline, superfluid and supersolid phases. Our predictions apply directly to current experiments with mesoscopic numbers of polar molecules and trapped ions.
NASA Astrophysics Data System (ADS)
Horwitz, L. P.; Land, Martin C.; Gill, Tepper; Lusanna, Luca; Salucci, Paolo
2013-04-01
Although the subject of relativistic dynamics has been explored, from both classical and quantum mechanical points of view, since the work of Einstein and Dirac, its most striking development has been in the framework of quantum field theory. The very accurate calculations of spectral and scattering properties, for example, of the anomalous magnetic moment of the electron and the Lamb shift in quantum electrodynamics, and many qualitative features of the strong and electroweak interactions, demonstrate the very great power of description achieved in this framework. Yet, many fundamental questions remain to be clarified, such as the structure of classical relativistic dynamical theories on the level of Hamilton and Lagrange in Minkowski space as well as on the curved manifolds of general relativity. There moreover remains the important question of the covariant classical description of systems at high energy for which particle production effects are not large, such as discussed in Synge's book, The Relativistic Gas, and in Balescu's book on relativistic statistical mechanics. In recent years, the study of high energy plasmas and heavy ion collisions has emphasized the importance of developing the techniques of relativistic mechanics. The results of Lindner et al [Physical Review Letters 95 0040401 (2005)] as well as the more recent proposal of Palacios et al [Phys. Rev. Lett. 103 253001 (2009)] and others, have shown that there must be a quantum theory with coherence in time. Such a theory, manifestly covariant under the transformations of special relativity with an invariant evolution parameter, such as that of Stueckelberg [Helv. Phys. Acta 14 322, 588 (1941); 15 23 (1942); see also R P Feynman Phys. Rev. 80 4401 and J S Schwinger Phys. Rev. 82 664 (1951)] could provide a suitable basis for the study of such questions, as well as many others for which the application of the standard methods of quantum field theory are difficult to manage, involving, in particular
NASA Astrophysics Data System (ADS)
Horwitz, Lawrence; Hu, Bei-Lok; Lee, Da-Shin; Gill, Tepper; Land, Martin
2011-12-01
Although the subject of relativistic dynamics has been explored from both classical and quantum mechanical points of view since the work of Einstein and Dirac, its most striking development has been in the framework of quantum field theory. The very accurate calculations of spectral and scattering properties, for example, of the anamolous magnetic moment of the electron and the Lamb shift in quantum electrodynamics, and many qualitative features of the strong and electroweak interactions, demonstrate the very great power of description achieved in this framework. Yet, many fundamental questions remain to be clarified, such as the structure of classical realtivistic dynamical theories on the level of Hamilton and Lagrange in Minkowski space as well as on the curved manifolds of general relativity. There moreover remains the important question of the covariant classical description of systems at high energy for which particle production effects are not large, such as discussed in Synge's book, The Relativistic Gas, and in Balescu's book on relativistic statistical mechanics. In recent years, the study of high energy plasmas and heavy ion collisions has emphasized the importance of developing the techniques of relativistic mechanics. The results of Linder et al (Phys. Rev. Lett. 95 0040401 (2005)) as well as the more recent work of Palacios et al (Phys. Rev. Lett. 103 253001 (2009)) and others, have shown that there must be a quantum theory with coherence in time. Such a theory, manifestly covariant under the transformations of special relativity with an invariant evolution parameter, such as that of Stueckelberg (Helv. Phys. Acta 14 322, 588 (1941); 15 23 (1942); see also R P Feynman Phys. Rev. 80 4401 and J S Schwinger Phys. Rev. 82 664 (1951)) could provide a suitable basis for the study of such questions, as well as many others for which the application of the standard methods of quantum field theory are difficult to manage, involving, in particular, local
NASA Astrophysics Data System (ADS)
Shebeko, A. V.; Shirokov, M. I.
2000-04-01
A growing interest in the method of unitary transformations (UT's) in the quantum theory of particles and nuclei has been seen during the last years. We express the total Hamiltonian H of interacting fields through new operators for particle creation and destruction and show that this can be understood as a UT of H. The respective particles may be called “cothed”. They are identified with the physical particles. The Hamiltonian in the new form turns out to be dependent on the renormalized particle masses and not the “bare” ones. Forms of the same kind are derived for all the Poincaré group generators. By using this new form of the Hamiltonian we suggest an approach to the bound state problem in relativistic quantum field theories (RQFT's). We also discuss applications of the developed formalism for constructing effective electromagnetic (EM) currents in the theory of photonuclear reactions.
Li, Wei-Li; Jian, Tian; Lopez, Gary V.; Wang, Lai-Sheng; Su, Jing; Hu, Han-Shi; Cao, Guo-Jin; Li, Jun
2014-03-07
The electronic structures of actinide systems are extremely complicated and pose considerable challenges both experimentally and theoretically because of significant electron correlation and relativistic effects. Here we report an investigation of the electronic structure and chemical bonding of uranium dioxides, UO{sub 2}{sup −} and UO{sub 2}, using photoelectron spectroscopy and relativistic quantum chemistry. The electron affinity of UO{sub 2} is measured to be 1.159(20) eV. Intense detachment bands are observed from the UO{sub 2}{sup −} low-lying (7sσ{sub g}){sup 2}(5fϕ{sub u}){sup 1} orbitals and the more deeply bound O2p-based molecular orbitals which are separated by a large energy gap from the U-based orbitals. Surprisingly, numerous weak photodetachment transitions are observed in the gap region due to extensive two-electron transitions, suggesting strong electron correlations among the (7sσ{sub g}){sup 2}(5fϕ{sub u}){sup 1} electrons in UO{sub 2}{sup −} and the (7sσ{sub g}){sup 1}(5fϕ{sub u}){sup 1} electrons in UO{sub 2}. These observations are interpreted using multi-reference ab initio calculations with inclusion of spin-orbit coupling. The strong electron correlations and spin-orbit couplings generate orders-of-magnitude more detachment transitions from UO{sub 2}{sup −} than expected on the basis of the Koopmans’ theorem. The current experimental data on UO{sub 2}{sup −} provide a long-sought opportunity to arbitrating various relativistic quantum chemistry methods aimed at handling systems with strong electron correlations.
NASA Astrophysics Data System (ADS)
Cufaro-Petroni, N.; Dewdney, C.; Holland, P.; Kyprianidis, T.; Vigier, J. P.
1985-09-01
The deduction by Guerra and Marra of the usual quantum operator algebra from a canonical variable Hamiltonian treatment of Nelson's hydrodynamical stochastic description of real nonrelativistic Schrödinger waves is extended to the causal stochastic interpretation given by Guerra and Ruggiero and by Vigier of relativistic Klein-Gordon waves. A specific representation shows that the Poisson brackets for canonical hydrodynamical observables become ``averages'' of quantum observables in the given state. Stochastic quantization thus justifies the standard procedure of replacing the classical particle (or field) observables with operators according to the scheme pμ-->-iħ∂μ and Lμν-->-iħ(xμ∂ν-xν∂μ).
Relativistic quantum nonlocality for the three-qubit Greenberger-Horne-Zeilinger state
Moradi, Shahpoor
2008-02-15
Lorentz transformation of the three-qubit Greenberger-Horne-Zeilinger (GHZ) state is studied. Also we obtain the relativistic spin joint measurement for the transformed state. Using these results it is shown that Bell's inequality is maximally violated for the three-qubit GHZ state in the relativistic regime. For ultrarelativistic particles we obtain the critical value for boost speed, which Bell's inequality is not violated for velocities smaller than this value. We also show that in the ultrarelativistic limit Bell's inequality is maximally violated for the GHZ state.
Heavy mesons spectra in a semi-analytical quantum relativistic approach
Mota, A. L.; Caldas, H.; Da Fonseca, J. E.
2013-03-25
The obtaining of bound states of heavy and light quarks interacting via a static quark potential is revisited here. We present an approach that both approximate the relativistic wave equation and allows the obtaining of analytical solutions and binding energies (and consequently, the heavy mesons spectra) of the system.
Relativistic geodesy and gravimetry with quantum sensors - on Earth and in Space
NASA Astrophysics Data System (ADS)
Flury, Jakob
2016-07-01
Quantum metrology and precision optical metrology enable new measurement techniques on the fields of inertial sensors, extremely precise ranging, atomic frequency standards and optical frequency transfer. Their precision level is highly relevant both for fundamental physics and for geodetic applications, including the monitoring of global and regional change processes in the frame of the Global Geodetic Observing System (GGOS). The Hannover Collaborative Research Center geo-Q focuses on the development of such techniques. We investigate laser interferometry in space - originally developed for gravitational wave astronomy - that can be used for inter-satellite ranging and for optical gravity gradiometry using multiple macroscopic testmasses in order to increase the resolution in satellite gravimetry. Prototypes for these techniques are flown on the LISA pathfinder and GRACE Follow-On missions. Complementarily, sensors based on atom interferometry are promising for accelerometry and gradiometry in terms of sensitivity, versatility and low systematic errors. Optical atomic clocks and optical frequency transfer allow tying gravitational measurements to an atomic reference, which could improve fundamental geodetic reference frames.
NASA Technical Reports Server (NTRS)
Brainerd, J. J.; Petrosian, V.
1987-01-01
Calculations are performed numerically and analytically of synchrotron spectra for thermal and power-law electron distributions using the single-particle synchrotron power spectrum derived from quantum electrodynamics. It is found that the photon energy at which quantum effects appear is proportional to temperature and independent of field strength for thermal spectra; quantum effects introduce an exponential roll-off away from the classical spectra. For power law spectra, the photon energy at which quantum effects appear is inversely proportional to the magnetic field strength; quantum effects produce a steeper power law than is found classically. The results are compared with spectra derived from the classical power spectrum with an energy cutoff ensuring conservation of energy. It is found that an energy cutoff is generally an inadequate approximation of quantum effects for low photon energies and for thermal spectra, but gives reasonable results for high-energy emission from power-law electron distributions.
Habibi, M.; Ghamari, F.
2014-05-15
The results of a numerical study of high-intensity X-ray laser beam interaction with warm quantum plasma (WQP) are presented. By means of an upward ramp density profile combined with quantum factors specially the Fermi velocity, we have demonstrated significant relativistic self-focusing (RSF) of a Gaussian electromagnetic beam in the WQP where the Fermi temperature term in the dielectric function is important. For this purpose, we have considered the quantum hydrodynamics model that modifies refractive index of inhomogeneous WQPs with the inclusion of quantum correction through the quantum statistical and diffraction effects in the relativistic regime. Also, to better illustration of the physical difference between warm and cold quantum plasmas and their effect on the RSF, we have derived the envelope equation governing the spot size of X-ray laser beam in Q-plasmas. In addition to the upward ramp density profile, we have found that the quantum effects would be caused much higher oscillation and better focusing of X-ray laser beam in the WQP compared to that of cold quantum case. Our computational results reveal the importance of the use of electrons density profile and Fermi speed in enhancing self-focusing of laser beam.
NASA Astrophysics Data System (ADS)
Lazur, V. Yu.; Pavlyk, O. F.; Reity, A. K.
2010-10-01
We solve the problem of interaction two quasimolecular electrons located at an arbitrary separation near different atoms (nuclei). We consider third-order effects in quantum electrodynamics, which include the virtual photon exchange between electrons with emission (absorption) of a real photon. We obtain the general expression for matrix elements of the operator of the effective interaction energy of two quasimolecular electrons with the external radiation field, which allows calculating probabilities of inelastic processes with rearrangement at slow collisions of multicharge ions with relativistic atoms. We demonstrate that consistently taking the natural condition of the interaction symmetry with respect to the two electrons into account results in the appearance of additional terms in the operators of spin-orbit, spin-spin, and retarded interactions compared with the previously obtained expressions for these operators. We construct the operator of the dipole-dipole interaction of two neutral atoms located at an arbitrary separation.
Dynamical symmetries of two-dimensional systems in relativistic quantum mechanics
NASA Astrophysics Data System (ADS)
Zhang, Fu-Lin; Song, Ci; Chen, Jing-Ling
2009-01-01
The two-dimensional Dirac Hamiltonian with equal scalar and vector potentials has been proved commuting with the deformed orbital angular momentum L. When the potential takes the Coulomb form, the system has an SO (3) symmetry, and similarly the harmonic oscillator potential possesses an SU (2) symmetry. The generators of the symmetric groups are derived for these two systems separately. The corresponding energy spectra are yielded naturally from the Casimir operators. Their non-relativistic limits are also discussed.
Contribution of relativistic quantum chemistry to electron's electric dipole moment for CP violation
NASA Astrophysics Data System (ADS)
Abe, M.; Gopakumar, G.; Das, B. P.; Tatewaki, H.; Mukherjee, D.; Hada, M.
2015-12-01
The search for the electric dipole moment of the electron (eEDM) is important because it is a probe of Charge Conjugation-Parity (CP) violation. It can also shed light on new physics beyond the standard model. It is not possible to measure the eEDM directly. However, the interaction energy involving the effective electric field (Eeff) acting on an electron in a molecule and the eEDM can be measured. This quantity can be combined with Eeff, which is calculated by relativistic molecular orbital theory to determine eEDM. Previous calculations of Eeff were not sufficiently accurate in the treatment of relativistic or electron correlation effects. We therefore developed a new method to calculate Eeff based on a four-component relativistic coupled-cluster theory. We demonstrated our method for YbF molecule, one of the promising candidates for the eEDM search. Using very large basis set and without freezing any core orbitals, we obtain a value of 23.1 GV/cm for Eeff in YbF with an estimated error of less than 10%. The error is assessed by comparison of our calculations and experiments for two properties relevant for Eeff, permanent dipole moment and hyperfine coupling constant. Our method paves the way to calculate properties of various kinds of molecules which can be described by a single-reference wave function.
Contribution of relativistic quantum chemistry to electron’s electric dipole moment for CP violation
Abe, M. Gopakumar, G. Hada, M.; Das, B. P.; Tatewaki, H.; Mukherjee, D.
2015-12-31
The search for the electric dipole moment of the electron (eEDM) is important because it is a probe of Charge Conjugation-Parity (CP) violation. It can also shed light on new physics beyond the standard model. It is not possible to measure the eEDM directly. However, the interaction energy involving the effective electric field (E{sub eff}) acting on an electron in a molecule and the eEDM can be measured. This quantity can be combined with E{sub eff}, which is calculated by relativistic molecular orbital theory to determine eEDM. Previous calculations of E{sub eff} were not sufficiently accurate in the treatment of relativistic or electron correlation effects. We therefore developed a new method to calculate E{sub eff} based on a four-component relativistic coupled-cluster theory. We demonstrated our method for YbF molecule, one of the promising candidates for the eEDM search. Using very large basis set and without freezing any core orbitals, we obtain a value of 23.1 GV/cm for E{sub eff} in YbF with an estimated error of less than 10%. The error is assessed by comparison of our calculations and experiments for two properties relevant for E{sub eff}, permanent dipole moment and hyperfine coupling constant. Our method paves the way to calculate properties of various kinds of molecules which can be described by a single-reference wave function.
Habibi, M.; Ghamari, F.
2014-06-15
Patil and Takale in their recent article [Phys. Plasmas 20, 072703 (2013)], by evaluating the quantum dielectric response in thermal quantum plasma, have modeled the relativistic self-focusing of Gaussian laser beam in a plasma. We have found that there are some important shortcomings and fundamental mistakes in Patil and Takale [Phys. Plasmas 20, 072703 (2013)] that we give a brief description about them and refer readers to important misconception about the use of the Fermi temperature in quantum plasmas, appearing in Patil and Takale [Phys. Plasmas 20, 072703 (2013)].
Quantum fluid model of coherent stimulated radiation by a dense relativistic cold electron beam
Monteiro, L. F.; Serbeto, A.; Tsui, K. H.; Mendonça, J. T.; Galvão, R. M. O.
2013-07-15
Using a quantum fluid model, the linear dispersion relation for FEL pumped by a short wavelength laser wiggler is deduced. Subsequently, a new quantum corrected resonance condition is obtained. It is shown that, in the limit of low energy electron beam and low frequency pump, the quantum recoil effect can be neglected, recovering the classical FEL resonance condition, k{sub s}=4k{sub w}γ{sup 2}. On the other hand, for short wavelength and high energy electron beam, the quantum recoil effect becomes strong and the resonance condition turns into k{sub s}=2√(k{sub w}/λ{sub c})γ{sup 3/2}, with λ{sub c} being the reduced Compton wavelength. As a result, a set of nonlinear coupled equations, which describes the quantum FEL dynamics as a three-wave interaction, is obtained. Neglecting wave propagation effects, this set of equations is solved numerically and results are presented.
NASA Astrophysics Data System (ADS)
Adesso, Gerardo; Ragy, Sammy; Girolami, Davide
2012-11-01
We review a recently introduced unified approach to the analytical quantification of correlations in Gaussian states of bosonic scalar fields by means of Rényi-2 entropy. This allows us to obtain handy formulae for classical, quantum, total correlations, as well as bipartite and multipartite entanglement. We apply our techniques to the study of correlations between two modes of a scalar field as described by observers in different states of motion. When one or both observers are in uniform acceleration, the quantum and classical correlations are degraded differently by the Unruh effect, depending on which mode is detected. Residual quantum correlations, in the form of quantum discord without entanglement, may survive in the limit of an infinitely accelerated observer Rob, provided they are revealed in a measurement performed by the inertial Alice.
Long-range quantum entanglement in noisy cluster states
Raussendorf, Robert; Bravyi, Sergey; Harrington, Jim
2005-06-15
We describe a phase transition for long-range entanglement in a three-dimensional cluster state affected by noise. The partially decohered state is modeled by the thermal state of a short-range translation-invariant Hamiltonian. We find that the temperature at which the entanglement length changes from infinite to finite is nonzero. We give an upper and lower bound to this transition temperature.
Schumaker, B.L.
1985-01-01
This thesis is a collection of six papers. The first four constitute the heart of the thesis; they are concerned with quantum-mechanical properties of certain harmonic-oscillator states. The first paper is a discourse on single-mode and two-mode Gaussian pure states (GPS), states produced when harmonic oscillators in their ground states are exposed to potentials that are linear or quadratic in oscillator position and momentum variables (creation and annihilation operators). The second and third papers develop a formalism for analyzing two photon devices (e.g., parametric amplifiers and phase-conjugate mirrors), in which photons in the output modes arise from two-proton transitions, i.e., are created or destroyed two at a time. The fourth paper is an analysis of the noise in homodyne detection, a phase-sensitive detection scheme in which the special properties of (single-mode) squeezed states are revealed. The fifth paper considers the validity of the standard quantum limit (SQL) for measurements that monitor the position of a free mass. The sixth paper develops the mathematical theory of torsional (toroidal) oscillations in fully general relativistic, nonrotating, spherical stellar models and of the gravitational waves they emit.
Numerical split-shift potential method for relativistic quantum systems with radial symmetry
NASA Astrophysics Data System (ADS)
Lv, Q. Z.; Norris, S.; Su, Q.; Grobe, R.
2016-03-01
We show how the spectrum of a radially symmetric Dirac Hamiltonian can be computed rather accurately on a spatial grid using a split-shift potential method. This method is sufficiently accurate such that the fine structure splittings of hydrogen-like relativistic ions with nuclear charge Z can be reproduced for a relatively small number of spatial radial grid points. We use this analytically known spectrum to examine the error scaling of this method. The method is then applied to examine the impact of a spatial confinement on the fine structure splittings and the bound states for hydrogen.
Guo, J. L.; Zhang, X. Z.
2016-01-01
Short-range interaction among the spins can not only results in the rich phase diagram but also brings about fascinating phenomenon both in the contexts of quantum computing and information. In this paper, we investigate the quantum correlation of the system coupled to a surrounding environment with short-range anisotropic interaction. It is shown that the decay of quantum correlation of the central spins measured by pairwise entanglement and quantum discord can serve as a signature of quantum phase transition. In addition, we study the decoherence factor of the system when the environment is in the vicinity of the phase transition point. In the strong coupling regime, the decay of the decoherence factor exhibits Gaussian envelop in the time domain. However, in weak coupling limit, the quantum correlation of the system is robust against the disturbance of the magnetic field through optimal control of the anisotropic short-range interaction strength. Based on this, the effects of the short-range anisotropic interaction on the sudden transition from classical to quantum decoherence are also presented. PMID:27596050
Guo, J L; Zhang, X Z
2016-01-01
Short-range interaction among the spins can not only results in the rich phase diagram but also brings about fascinating phenomenon both in the contexts of quantum computing and information. In this paper, we investigate the quantum correlation of the system coupled to a surrounding environment with short-range anisotropic interaction. It is shown that the decay of quantum correlation of the central spins measured by pairwise entanglement and quantum discord can serve as a signature of quantum phase transition. In addition, we study the decoherence factor of the system when the environment is in the vicinity of the phase transition point. In the strong coupling regime, the decay of the decoherence factor exhibits Gaussian envelop in the time domain. However, in weak coupling limit, the quantum correlation of the system is robust against the disturbance of the magnetic field through optimal control of the anisotropic short-range interaction strength. Based on this, the effects of the short-range anisotropic interaction on the sudden transition from classical to quantum decoherence are also presented. PMID:27596050
Nakata, Ayako; Tsuneda, Takao; Hirao, Kimihiko
2011-12-14
A long-range corrected (LC) time-dependent density functional theory (TDDFT) incorporating relativistic effects with spin-orbit couplings is presented. The relativistic effects are based on the two-component zeroth-order regular approximation Hamiltonian. Before calculating the electronic excitations, we calculated the ionization potentials (IPs) of alkaline metal, alkaline-earth metal, group 12 transition metal, and rare gas atoms as the minus orbital (spinor) energies on the basis of Koopmans' theorem. We found that both long-range exchange and spin-orbit coupling effects are required to obtain Koopmans' IPs, i.e., the orbital (spinor) energies, quantitatively in DFT calculations even for first-row transition metals and systems containing large short-range exchange effects. We then calculated the valence excitations of group 12 transition metal atoms and the Rydberg excitations of rare gas atoms using spin-orbit relativistic LC-TDDFT. We found that the long-range exchange and spin-orbit coupling effects significantly contribute to the electronic spectra of even light atoms if the atoms have low-lying excitations between orbital spinors of quite different electron distributions.
NASA Astrophysics Data System (ADS)
Haba, Z.
2009-02-01
We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.
Haba, Z
2009-02-01
We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed. PMID:19391727
Quantum Particles From Quantum Information
NASA Astrophysics Data System (ADS)
Görnitz, T.; Schomäcker, U.
2012-08-01
Many problems in modern physics demonstrate that for a fundamental entity a more general conception than quantum particles or quantum fields are necessary. These concepts cannot explain the phenomena of dark energy or the mind-body-interaction. Instead of any kind of "small elementary building bricks", the Protyposis, an abstract and absolute quantum information, free of special denotation and open for some purport, gives the solution in the search for a fundamental substance. However, as long as at least relativistic particles are not constructed from the Protyposis, such an idea would remain in the range of natural philosophy. Therefore, the construction of relativistic particles without and with rest mass from quantum information is shown.
Avetissian, H K; Ghazaryan, A G; Matevosyan, H H; Mkrtchian, G F
2015-10-01
The microscopic quantum theory of plasma nonlinear interaction with the coherent shortwave electromagnetic radiation of arbitrary intensity is developed. The Liouville-von Neumann equation for the density matrix is solved analytically considering a wave field exactly and a scattering potential of plasma ions as a perturbation. With the help of this solution we calculate the nonlinear inverse-bremsstrahlung absorption rate for a grand canonical ensemble of electrons. The latter is studied in Maxwellian, as well as in degenerate quantum plasma for x-ray lasers at superhigh intensities and it is shown that one can achieve the efficient absorption coefficient in these cases. PMID:26565352
NASA Astrophysics Data System (ADS)
Flury, J.
2016-06-01
Quantum metrology enables new applications in geodesy, including relativistic geodesy. The recent progress in optical atomic clocks and in long-distance frequency transfer by optical fiber together pave the way for using measurements of the gravitational frequency redshift for geodesy. The remote comparison of frequencies generated by calibrated clocks will allow for a purely relativistic determination of differences in gravitational potential and height between stations on Earth surface (chronometric leveling). The long-term perspective is to tie potential and height differences to atomic standards in order to overcome the weaknesses and inhomogeneity of height systems determined by classical spirit leveling. Complementarily, gravity measurements with atom interferometric setups, and satellite gravimetry with space borne laser interferometers allow for new sensitivities in the measurement of the Earth's gravity field.
NASA Astrophysics Data System (ADS)
Moradi, Afshin
2016-07-01
In a recent paper Abdel Aziz [Phys. Lett. A 376 (2012) 169] obtained the dispersion properties of TE surface modes propagating at the interface between a magnetized quantum plasma and vacuum in the Faraday configuration, where these TE surface waves are excited during the interaction of relativistic electron beam with magnetized quantum plasma. The present Comment points out that in the Faraday configuration the surface waves acquire both TM and TE components due to the cyclotron motion of electrons. Therefore, the TE surface waves cannot propagate on surface of the present system and the general dispersion relations for surface waves, derived by Abdel Aziz are incorrect.
Quantum phases from competing short- and long-range interactions in an optical lattice.
Landig, Renate; Hruby, Lorenz; Dogra, Nishant; Landini, Manuele; Mottl, Rafael; Donner, Tobias; Esslinger, Tilman
2016-04-28
Insights into complex phenomena in quantum matter can be gained from simulation experiments with ultracold atoms, especially in cases where theoretical characterization is challenging. However, these experiments are mostly limited to short-range collisional interactions; recently observed perturbative effects of long-range interactions were too weak to reach new quantum phases. Here we experimentally realize a bosonic lattice model with competing short- and long-range interactions, and observe the appearance of four distinct quantum phases--a superfluid, a supersolid, a Mott insulator and a charge density wave. Our system is based on an atomic quantum gas trapped in an optical lattice inside a high-finesse optical cavity. The strength of the short-range on-site interactions is controlled by means of the optical lattice depth. The long (infinite)-range interaction potential is mediated by a vacuum mode of the cavity and is independently controlled by tuning the cavity resonance. When probing the phase transition between the Mott insulator and the charge density wave in real time, we observed a behaviour characteristic of a first-order phase transition. Our measurements have accessed a regime for quantum simulation of many-body systems where the physics is determined by the intricate competition between two different types of interactions and the zero point motion of the particles. PMID:27064902
Quantum phases from competing short- and long-range interactions in an optical lattice
NASA Astrophysics Data System (ADS)
Landig, Renate; Hruby, Lorenz; Dogra, Nishant; Landini, Manuele; Mottl, Rafael; Donner, Tobias; Esslinger, Tilman
2016-04-01
Insights into complex phenomena in quantum matter can be gained from simulation experiments with ultracold atoms, especially in cases where theoretical characterization is challenging. However, these experiments are mostly limited to short-range collisional interactions; recently observed perturbative effects of long-range interactions were too weak to reach new quantum phases. Here we experimentally realize a bosonic lattice model with competing short- and long-range interactions, and observe the appearance of four distinct quantum phases—a superfluid, a supersolid, a Mott insulator and a charge density wave. Our system is based on an atomic quantum gas trapped in an optical lattice inside a high-finesse optical cavity. The strength of the short-range on-site interactions is controlled by means of the optical lattice depth. The long (infinite)-range interaction potential is mediated by a vacuum mode of the cavity and is independently controlled by tuning the cavity resonance. When probing the phase transition between the Mott insulator and the charge density wave in real time, we observed a behaviour characteristic of a first-order phase transition. Our measurements have accessed a regime for quantum simulation of many-body systems where the physics is determined by the intricate competition between two different types of interactions and the zero point motion of the particles.
Effect of relativistic acceleration on localized two-mode Gaussian quantum states
NASA Astrophysics Data System (ADS)
Ahmadi, Mehdi; Lorek, Krzysztof; Checińska, Agata; Smith, Alexander R. H.; Mann, Robert B.; Dragan, Andrzej
2016-06-01
We study how an arbitrary Gaussian state of two localized wave packets, prepared in an inertial frame of reference, is described by a pair of uniformly accelerated observers. We explicitly compute the resulting state for arbitrarily chosen proper accelerations of the observers and independently tuned distance between them. To do so, we introduce a generalized Rindler frame of reference and analytically derive the corresponding state transformation as a Gaussian channel. Our approach provides several new insights into the phenomenon of vacuum entanglement such as the highly nontrivial effect of spatial separation between the observers including sudden death of entanglement. We also calculate the fidelity of the two-mode channel for nonvacuum Gaussian states and obtain bounds on classical and quantum capacities of a single-mode channel. Our framework can be directly applied to any continuous variable quantum information protocol in which the effects of acceleration or gravity cannot be neglected.
Quantum heat engine in the relativistic limit: the case of a Dirac particle.
Muñoz, Enrique; Peña, Francisco J
2012-12-01
We studied the efficiency of two different schemes for a quantum heat engine, by considering a single Dirac particle trapped in an infinite one-dimensional potential well as the "working substance." The first scheme is a cycle, composed of two adiabatic and two isoenergetic reversible trajectories in configuration space. The trajectories are driven by a quasistatic deformation of the potential well due to an external applied force. The second scheme is a variant of the former, where isoenergetic trajectories are replaced by isothermal ones, along which the system is in contact with macroscopic thermostats. This second scheme constitutes a quantum analog of the classical Carnot cycle. Our expressions, as obtained from the Dirac single-particle spectrum, converge in the nonrelativistic limit to some of the existing results in the literature for the Schrödinger spectrum. PMID:23367894
NASA Astrophysics Data System (ADS)
Horwitz, L. P.
2015-05-01
The most recent meeting took place at the University of Connecticut, Storrs, on June 9-13, 2014. This meeting forms the basis for the Proceedings that are recorded in this issue of the Journal of Physics: Conference Series. Along with the work of some of the founding members of the Association, we were fortunate to have lecturers from application areas that provided strong challenges for further developments in quantum field theory, cosmological problems, and in the dynamics of systems subject to accelerations and the effects of general relativity. Topics treated in this issue include studies of the dark matter problem, rotation curves, and, in particular, for the (relatively accessible) Milky Way galaxy, compact stellar objects, a composite particle model, and the properties of a conformally invariant theory with spontaneous symmetry breaking. The Stueckelberg theory is further investigated for its properties in producing bremsstrahlung and pair production and apparent superluminal effects, and, as mentioned above, the implications of low energy nuclear reactions for such off-shell theories. Other "proper time" theories are investigated as well, and a study of the clock synchronization problem is presented. A mathematical study of to quantum groupo associated with the Toda lattice and its implications for quantum field theory, as well as a phenomenological discussion of supernova mechanics as well as a semiclassical discussion of electron spin and the question of the compatibility of special relativity and the quantum theory. A careful analysis of the covariant Aharonov-Bohm effect is given as well. The quantization of massless fields and the relation to the Maxwell theory is also discussed. We wish to thank the participants who contributed very much through their lectures, personal discussions, and these papers, to the advancement of the subject and our understanding.
Bliokh, Konstantin Y; Nori, Franco
2012-03-23
We consider the relativistic deformation of quantum waves and mechanical bodies carrying intrinsic angular momentum (AM). When observed in a moving reference frame, the centroid of the object undergoes an AM-dependent transverse shift. This is the relativistic analogue of the spin-Hall effect, which occurs in free space without any external fields. Remarkably, the shifts of the geometric and energy centroids differ by a factor of 2, and both centroids are crucial for the Lorentz transformations of the AM tensor. We examine manifestations of the relativistic Hall effect in quantum vortices and mechanical flywheels and also discuss various fundamental aspects of this phenomenon. The perfect agreement of quantum and relativistic approaches allows applications at strikingly different scales, from elementary spinning particles, through classical light, to rotating black holes. PMID:22540559
NASA Astrophysics Data System (ADS)
Wang, Tianyi; Yu, Song; Gu, Wanyi
2016-03-01
In continuous-variable quantum key distribution, detectors are necessarily coarse grained and of finite range. We analyze the impact of both features and demonstrate that while coarse graining adds a fixed error to the estimated excess noise, finite range degrades the estimation accuracy of both transmission and excess noise. Moreover, the inaccurate estimation due to finite range may results in secret key rate underestimation, even misjudgment of security. To compensate these consequences, tuning the modulation variance is a possible way.
Pricing of range accrual swap in the quantum finance Libor Market Model
NASA Astrophysics Data System (ADS)
Baaquie, Belal E.; Du, Xin; Tang, Pan; Cao, Yang
2014-05-01
We study the range accrual swap in the quantum finance formulation of the Libor Market Model (LMM). It is shown that the formulation can exactly price the path dependent instrument. An approximate price is obtained as an expansion in the volatility of Libor. The Monte Carlo simulation method is used to study the nonlinear domain of the model and determine the range of validity of the approximate formula. The price of accrual swap is analyzed by generating daily sample values by simulating a two dimension Gaussian quantum field.
Short-range quantum magnetism of ultracold fermions in an optical lattice.
Greif, Daniel; Uehlinger, Thomas; Jotzu, Gregor; Tarruell, Leticia; Esslinger, Tilman
2013-06-14
Quantum magnetism originates from the exchange coupling between quantum mechanical spins. Here, we report on the observation of nearest-neighbor magnetic correlations emerging in the many-body state of a thermalized Fermi gas in an optical lattice. The key to obtaining short-range magnetic order is a local redistribution of entropy, which allows temperatures below the exchange energy for a subset of lattice bonds. When loading a repulsively interacting gas into either dimerized or anisotropic simple cubic configurations of a tunable-geometry lattice, we observe an excess of singlets as compared with triplets consisting of two opposite spins. For the anisotropic lattice, the transverse spin correlator reveals antiferromagnetic correlations along one spatial axis. Our work facilitates addressing open problems in quantum magnetism through the use of quantum simulation. PMID:23704375
NASA Astrophysics Data System (ADS)
Flury, Jakob; Müller, Jürgen
2016-04-01
The recent breakthroughs in long-distance frequency comparisons of Strontium optical atomic clocks through phase-stabilized optical fibers open a new field for geodesy. The results obtained are already consistent with the expected gravitational frequency redshift between the involved stations at a level that corresponds to an inaccuracy of less than 1 m in height difference, and an improvement towards the cm accuracy level is expected rather soon. Particularly interesting is the fundamentally new perspective of tying potential differences and height differences to an atomic reference. Potential applications include regional geoid determination and the connection of height systems and tide gauges. In a broader view, quantum metrology offers many options for gravity related measurements. For optical clocks, relevant levels of precision and accuracy are obtained from a rather large variety of atomic species, both for clocks interrogating many neutral atoms in optical lattices, and for single-ion clocks using quantum logic that enables accessing particularly favorable atomic transitions. To assess the advantages of the different options and to choose specific setups is a challenge both for the re-definition of the SI second and for geodetic applications. Similarly, and closely related, atom interferometry offers many options for gravity related measurements. Different species in a variety of setups are being used successfully to determine gravity accelerations and its spatial derivatives.
NASA Astrophysics Data System (ADS)
da Silva, Robson; Hoff, Diego A.; Rego, Luis G. C.
2015-04-01
Charge and excitonic-energy transfer phenomena are fundamental for energy conversion in solar cells as well as artificial photosynthesis. Currently, much interest is being paid to light-harvesting and energy transduction processes in supramolecular structures, where nuclear dynamics has a major influence on electronic quantum dynamics. For this reason, the simulation of long range electron transfer in supramolecular structures, under environmental conditions described within an atomistic framework, has been a difficult problem to study. This work describes a coupled quantum mechanics/molecular mechanics method that aims at describing long range charge transfer processes in supramolecular systems, taking into account the atomistic details of large molecular structures, the underlying nuclear motion, and environmental effects. The method is applied to investigate the relevance of electron-nuclei interaction on the mechanisms for photo-induced electron-hole pair separation in dye-sensitized interfaces as well as electronic dynamics in molecular structures.
Nakanishi, Masakazu
2014-10-15
Responses of a superconducting quantum interference device (SQUID) are periodically dependent on magnetic flux coupling to its superconducting ring and the period is a flux quantum (Φ{sub o} = h/2e, where h and e, respectively, express Planck's constant and elementary charge). Using this periodicity, we had proposed a digital to analog converter using a SQUID (SQUID DAC) of first generation with linear current output, interval of which corresponded to Φ{sub o}. Modification for increasing dynamic range by interpolating within each interval is reported. Linearity of the interpolation was also based on the quantum periodicity. A SQUID DAC with dynamic range of about 1.4 × 10{sup 7} was created as a demonstration.
NASA Astrophysics Data System (ADS)
Potylitsyn, A. P.; Kolchuzhkin, A. M.; Strokov, S. A.
2016-07-01
A photon spectrum of undulator radiation (UR) is calculated in the semi-classical approach. The UR intensity spectrum is determined by an electron trajectory in the undulator neglecting by energy losses for radiation. Using the Planck's law, the UR photon spectrum can be calculated from the classical intensity spectrum both for linear and nonlinear regimes. The radiation of an electron in a field of strong electromagnetic wave (radiation in the "light" undulator) is considered in the quantum electromagnetic frame. Comparison of results obtained by both approaches has been shown that UR spectra in the whole cone coincide with high accuracy for the case x<<1. Characteristics of the collimated UR beam were simulated with taking into account the discrete process of photon emission along an electron trajectory in both kinds of undulators.
NASA Astrophysics Data System (ADS)
Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Hauer, M.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Seals, H.; Sedykh, I.; Skulski, W.; Smith, C. E.; Stankiewicz, M. A.; Steinberg, P.; Stephans, G. S.; Sukhanov, A.; Tang, J.-L.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Wenger, E.; Wolfs, F. L.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.
2005-04-01
This Letter describes the measurement of the energy dependence of elliptic flow for charged particles in Au+Au collisions using the PHOBOS detector at the Relativistic Heavy Ion Collider. Data taken at collision energies of √(sNN)=19.6, 62.4, 130, and 200 GeV are shown over a wide range in pseudorapidity. These results, when plotted as a function of η'=|η|-ybeam, scale with approximate linearity throughout η', implying no sharp changes in the dynamics of particle production as a function of pseudorapidity or increasing beam energy.
Adiabatic two-photon quantum gate operations using a long-range photonic bus
NASA Astrophysics Data System (ADS)
Hope, Anthony P.; Nguyen, Thach G.; Mitchell, Arnan; Greentree, Andrew D.
2015-03-01
Adiabatic techniques have much potential to realize practical and robust optical waveguide devices. Traditionally, photonic elements are limited to coupling schemes that rely on proximity to nearest neighbour elements. We combine adiabatic passage with a continuum based long-range optical bus to break free from such topological restraints and thereby outline a new approach to photonic quantum gate design. We explicitly show designs for adiabatic quantum gates that produce a Hadamard, 50:50 and 1/3:2/3 beam splitter, and non-deterministic controlled NOT gate based on planar thin, shallow ridge waveguides. Our calculations are performed under conditions of one and two-photon inputs.
Perturbative instability of quantum memory based on effective long-range interactions
NASA Astrophysics Data System (ADS)
Landon-Cardinal, Olivier; Yoshida, Beni; Poulin, David; Preskill, John
2015-03-01
A two-dimensional topologically ordered quantum memory is well protected against error if the energy gap is large compared to the temperature, but this protection does not improve as the system size increases. We review and critique some recent proposals for improving the memory time by introducing long-range interactions among anyons, noting that instability with respect to small local perturbations of the Hamiltonian is a generic problem for such proposals. We also discuss some broader issues regarding the prospects for scalable quantum memory in two-dimensional systems.
Relative orbit determination for satellite formation flying based on quantum ranging
NASA Astrophysics Data System (ADS)
Shen, Yanghe; Xu, Luping; Zhang, Hua; Chen, Shanshan; Song, Shibin
2015-08-01
Relative orbit determination is widely used in the field of autonomously controlled satellite formation flying (SFF). Currently, some traditional techniques cannot meet the strict requirement of the accuracy of relative orbit determination for certain space missions. Thus, the primary purpose of this study is to design some special type of sensor to increase the accuracy of the distance measurement, which can eventually lead to an improvement in the accuracy of relative orbit determination for SFF. Two types of quantum sensors are proposed, based on the double-points quantum ranging (DPQR) and the triangle quantum ranging (TQR) schemes that utilize the second-order correlation between the entangled photons. Simulation result shows that the ranging accuracy of the TQR-type sensor is more precise than that of the DPQR-type one. Additionally, the unscented Kalman filter (UKF) is used to estimate the relative state of the SFF, which uses the TQR-type sensor as the measurement model compared with a traditional sensor. The simulation results show that the quantum sensor is superior to the traditional one and their estimation errors of the position and velocity remain within 1 cm and 1 mm/s, respectively, at a relative distance of 1 km between the chief and deputy satellites.
Weakly relativistic plasma expansion
Fermous, Rachid Djebli, Mourad
2015-04-15
Plasma expansion is an important physical process that takes place in laser interactions with solid targets. Within a self-similar model for the hydrodynamical multi-fluid equations, we investigated the expansion of both dense and under-dense plasmas. The weakly relativistic electrons are produced by ultra-intense laser pulses, while ions are supposed to be in a non-relativistic regime. Numerical investigations have shown that relativistic effects are important for under-dense plasma and are characterized by a finite ion front velocity. Dense plasma expansion is found to be governed mainly by quantum contributions in the fluid equations that originate from the degenerate pressure in addition to the nonlinear contributions from exchange and correlation potentials. The quantum degeneracy parameter profile provides clues to set the limit between under-dense and dense relativistic plasma expansions at a given density and temperature.
Exact Diagonalization of a Quantum XXZ Model with Long-Range Interactions
NASA Astrophysics Data System (ADS)
Williams, Justin A.; Smith, David A.; Wang, C. C.-Joseph; Varney, Christopher N.
In recent years, rapid advancement has been made in using ultra-cold gases as quantum spin simulators, with two dimensional lattices becoming a rich target for exploring the exotic states and excitations of spin-1/2 systems on frustrated lattices. When the interaction in the system becomes long-ranged, the spins are frustrated by the long-range interaction. Consequently, the competition between the geometric frustration and the long-range interaction results in the the underlying orders present in the ground state being unclear. Here, we investigate the quantum dipolar XXZ model with exact diagonalization to characterize and contrast the ground state and excitations on square and triangular lattices to provide a baseline for comparison with experiments. University of West Florida Summer Undergraduate Research Program, University of West Florida Quality Enhancement Plan Award.
Long-range quantum gate via Rydberg states of atoms in a thermal microwave cavity
NASA Astrophysics Data System (ADS)
Sárkány, Lőrinc; Fortágh, József; Petrosyan, David
2015-09-01
We propose an implementation of a universal quantum gate between pairs of spatially separated atoms in a microwave cavity at finite temperature. The gate results from reversible laser excitation of Rydberg states of atoms interacting with each other via exchange of virtual photons through a common cavity mode. Quantum interference of different transition paths between the two-atom ground and double-excited Rydberg states makes both the transition amplitude and resonance largely insensitive to the excitations in the microwave cavity quantum bus which can therefore be in any superposition or mixture of photon number states. Our scheme for attaining ultra-long-range interactions and entanglement also applies to mesoscopic atomic ensembles in the Rydberg blockade regime and is scalable to many ensembles trapped within a centimeter-sized microwave resonator.
Tripathi, L. N.; Praveena, M.; Valson, Pranay; Basu, J. K.
2014-10-20
Quantum dot arrays have been projected as the material of choice for next generation displays and photodetectors. Extensive ongoing research aims at improving optical and electrical efficiencies of such devices. We report experimental results on non-local long range emission intensity enhancement and anisotropy in quantum dot assemblies induced by isolated and partially aligned gold nanoantennas. Spatially resolved photoluminescence clearly demonstrate that the effect is maximum, when the longitudinal surface plasmon resonance of the nanoantenna is resonant with the emission maxima of the quantum dots. We estimated the decay length of this enhancement to be ∼2.6 μm, which is considerably larger than the range of near field interaction of metal nanoantenna. Numerical simulations qualitatively capture the near field behavior of the nanorods but fail to match the experimentally observed non-local effects. We have suggested how strong interactions of quantum dots in the close packed assemblies, mediated by the nanoantennas, could lead to such observed behavior.
NASA Astrophysics Data System (ADS)
Wang, Hai Tao; Cho, Sam Young
2015-01-01
In order to investigate the quantum phase transition in the one-dimensional quantum compass model, we numerically calculate non-local string correlations, entanglement entropy and fidelity per lattice site by using the infinite matrix product state representation with the infinite time evolving block decimation method. In the whole range of the interaction parameters, we find that four distinct string orders characterize the four different Haldane phases and the topological quantum phase transition occurs between the Haldane phases. The critical exponents of the string order parameters β = 1/8 and the cental charges c = 1/2 at the critical points show that the topological phase transitions between the phases belong to an Ising type of universality classes. In addition to the string order parameters, the singularities of the second derivative of the ground state energies per site, the continuous and singular behaviors of the Von Neumann entropy and the pinch points of the fidelity per lattice site manifest that the phase transitions between the phases are of the second-order, in contrast to the first-order transition suggested in previous studies.
Wang, Hai Tao; Cho, Sam Young
2015-01-14
In order to investigate the quantum phase transition in the one-dimensional quantum compass model, we numerically calculate non-local string correlations, entanglement entropy and fidelity per lattice site by using the infinite matrix product state representation with the infinite time evolving block decimation method. In the whole range of the interaction parameters, we find that four distinct string orders characterize the four different Haldane phases and the topological quantum phase transition occurs between the Haldane phases. The critical exponents of the string order parameters β = 1/8 and the cental charges c = 1/2 at the critical points show that the topological phase transitions between the phases belong to an Ising type of universality classes. In addition to the string order parameters, the singularities of the second derivative of the ground state energies per site, the continuous and singular behaviors of the Von Neumann entropy and the pinch points of the fidelity per lattice site manifest that the phase transitions between the phases are of the second-order, in contrast to the first-order transition suggested in previous studies. PMID:25478955
NASA Astrophysics Data System (ADS)
Valente, Giovanni; Owen Weatherall, James
2014-11-01
Relativity theory is often taken to include, or to imply, a prohibition on superluminal propagation of causal processes. Yet, what exactly the prohibition on superluminal propagation amounts to and how one should deal with its possible violation have remained open philosophical problems, both in the context of the metaphysics of causation and the foundations of physics. In particular, recent work in philosophy of physics has focused on the causal structure of spacetime in relativity theory and on how this causal structure manifests itself in our most fundamental theories of matter. These topics were the subject of a workshop on "Relativistic Causality in Quantum Field Theory and General Relativity" that we organized (along with John Earman) at the Center for Philosophy of Science in Pittsburgh on April 5-7, 2013. The present Special Issue comprises contributions by speakers in that workshop as well as several other experts exploring different aspects of relativistic causality. We are grateful to the journal for hosting this Special Issue, to the journal's managing editor, Femke Kuiling, for her help and support in putting the issue together, and to the authors and the referees for their excellent work.
Perspective: relativistic effects.
Autschbach, Jochen
2012-04-21
This perspective article discusses some broadly-known and some less broadly-known consequences of Einstein's special relativity in quantum chemistry, and provides a brief outline of the theoretical methods currently in use, along with a discussion of recent developments and selected applications. The treatment of the electron correlation problem in relativistic quantum chemistry methods, and expanding the reach of the available relativistic methods to calculate all kinds of energy derivative properties, in particular spectroscopic and magnetic properties, requires on-going efforts. PMID:22519307
Effects of long-range hopping and interactions on quantum walks in ordered and disordered lattices
NASA Astrophysics Data System (ADS)
Chattaraj, T.; Krems, R. V.
2016-08-01
We study the effects of long-range hopping and long-range interparticle interactions on the quantum walk of hard-core bosons in ideal and disordered one-dimensional lattices. We find that the range of hopping has a much more significant effect on the particle correlation dynamics than the range of interactions. We illustrate that long-range hopping makes the correlation diagrams asymmetric with respect to the sign of the interaction. We examine the relative role of repulsive and attractive interactions on the dynamics of scattering by isolated impurities and Anderson localization in disordered lattices. We show that weakly repulsive interactions increase the probability of tunneling through isolated impurities and decrease the localization.
NASA Astrophysics Data System (ADS)
Ray, Megan R.; van Enk, S. J.
2013-10-01
In continuous-variable quantum information processing, detectors are necessarily coarse grained and of finite range. We discuss how, especially, the latter feature is a bug and may easily lead to overoptimistic estimates of entanglement and of security when missed data outside the detector range are ignored. We demonstrate that a straightforward worst-case analysis is sufficient to avoid false positive statements about entanglement. We show that, for our worst-case analysis, entropic separability or security criteria are much superior to variance-based criteria.
A Simple Relativistic Bohr Atom
ERIC Educational Resources Information Center
Terzis, Andreas F.
2008-01-01
A simple concise relativistic modification of the standard Bohr model for hydrogen-like atoms with circular orbits is presented. As the derivation requires basic knowledge of classical and relativistic mechanics, it can be taught in standard courses in modern physics and introductory quantum mechanics. In addition, it can be shown in a class that…
NASA Astrophysics Data System (ADS)
Xia, Lifang
In the first part of this thesis, we use the generalized Landau-level represen- tation to study the effect of screening on the properties of the graphene quantum Hall states with integer filling factors. The analysis is performed in the low-energy Dirac model in the mean-field approximation, in which the long-range Coulomb in- teraction is modified by the one-loop static screening effects. The solutions demon- strate that static screening leads to a substantial suppression of the gap parameters in the quantum Hall states with a broken U (4) flavor symmetry. The results of the temperature dependence of the energy gaps mimic well the temperature dependence of the activation energies measured in experiment. The Landau-level running of the quasiparticle dynamical parameters could be tested via optical studies of the integer quantum Hall states. In the second part, by using the generalized Landau-level representation, we study the interaction induced chiral asymmetry in cold QED plasma beyond the weak-field approximation. The chiral shift and the parity-even chiral chemical potential function are obtained numerically and are found peaking near the Fermi surface and increases and decreases with the Landau level index, respectively. The results are used to quantify the chiral asymmetry of the Fermi surface in dense QED matter. The chiral asymmetry appears to be rather small even in the strongest mag- netic fields and at the highest stellar densities. However, the analogous asymmetry can be substantial in the case of dense quark matter.
Quantum spin dynamics and entanglement in systems with long-range interactions
NASA Astrophysics Data System (ADS)
Rey, Ana M.
One of the fundamental goals of modern quantum sciences is to learn how to control and manipulate non-equilibrium many-body systems and use them to make powerful and improved quantum devices, materials and technologies. However, out-of-equilibrium systems are complex, typically strongly correlated and entangled, and thus to model them we are in an urgent need of new methodologies. In this talk I will discuss new theoretical methods that we have developed to investigate emergent non-equilibrium phenomena in driven-dissipative spin systems interacting via long-range interactions. I will show we can capture the dynamics of correlations and entanglement in close systems and the interplay between dissipation and entanglement in open quantum systems including spin-boson models. As a specific application I will discuss the use of our methods to model the spin dynamics exhibited by arrays of trapped ions with controllable long-range interactions. I will show that our predictions are consistent with recent experimental measurements. I will also discuss new protocols to diagnostic and characterize entanglement based on well-established NMR protocols This work is supported by NSF, ARO, AFOSR-MURI, and NIST.
NASA Astrophysics Data System (ADS)
Seilmeier, F.; Hauck, M.; Schubert, E.; Schinner, G. J.; Beavan, S. E.; Högele, A.
2014-08-01
We show how resonant laser spectroscopy of the trion optical transitions in a self-assembled quantum dot can be used to determine the temperature of a nearby electron reservoir. At finite magnetic field, the spin-state occupation of the Zeeman-split quantum-dot electron ground states is governed by thermalization with the electron reservoir via cotunneling. With resonant spectroscopy of the corresponding excited trion states, we map out the spin occupation as a function of magnetic field to establish optical thermometry for the electron reservoir. We demonstrate the implementation of the technique in the subkelvin temperature range where it is most sensitive and where the electron temperature is not necessarily given by the cryostat base temperature.
Quantum transport with long-range steps on Watts-Strogatz networks
NASA Astrophysics Data System (ADS)
Wang, Yan; Xu, Xin-Jian
2016-07-01
We study transport dynamics of quantum systems with long-range steps on the Watts-Strogatz network (WSN) which is generated by rewiring links of the regular ring. First, we probe physical systems modeled by the discrete nonlinear schrödinger (DNLS) equation. Using the localized initial condition, we compute the time-averaged occupation probability of the initial site, which is related to the nonlinearity, the long-range steps and rewiring links. Self-trapping transitions occur at large (small) nonlinear parameters for coupling ɛ=-1 (1), as long-range interactions are intensified. The structure disorder induced by random rewiring, however, has dual effects for ɛ=-1 and inhibits the self-trapping behavior for ɛ=1. Second, we investigate continuous-time quantum walks (CTQW) on the regular ring ruled by the discrete linear schrödinger (DLS) equation. It is found that only the presence of the long-range steps does not affect the efficiency of the coherent exciton transport, while only the allowance of random rewiring enhances the partial localization. If both factors are considered simultaneously, localization is greatly strengthened, and the transport becomes worse.
Samanta, Anirban; Zhou, Yadong; Zou, Shengli; Yan, Hao; Liu, Yan
2014-09-10
The dependence of quantum dot (QD) fluorescence emission on the proximity of 30 nm gold nanoparticles (AuNPs) was studied with controlled interparticle distances ranging from 15 to 70 nm. This was achieved by coassembling DNA-conjugated QDs and AuNPs in a 1:1 ratio at precise positions on a triangular-shaped DNA origami platform. A profound, long-range quenching of the photoluminescence intensity of the QDs was observed. A combination of static and time-resolved fluorescence measurements suggests that the quenching is due to an increase in the nonradiative decay rate of QD emission. Unlike FRET, the energy transfer is inversely proportional to the 2.7th power of the distance between nanoparticles with half quenching at ∼28 nm. This long-range quenching phenomena may be useful for developing extended spectroscopic rulers in the future. PMID:25084363
Slow dynamics in many-body quantum systems with long range interactions
NASA Astrophysics Data System (ADS)
Santos, Lea; Perez-Bernal, Francisco
2016-05-01
In recent experiments with ion traps the range of the interactions between spins-1/2 can be controlled. In the limit of infinite-range interaction the system may be described by the Lipkin model, which exhibits an excited state quantum phase transition (ESQPT). The latter corresponds to a singularity in the spectrum that occurs at the ground state and propagates to higher energies as the control parameter increases beyond the ground state critical point. We show that the evolution of an initial state with energy close to the ESQPT critical point may be extremely slow. This result is surprising, since the dynamics is usually expected to be very fast in systems with long-range interactions. This behavior is justified with the analysis of the structures of the eigenstates. This work was supported by the NSF Grant No. DMR-1147430.
Auxiliary-field quantum Monte Carlo calculations for systems with long-range repulsive interactions
Silvestrelli, P.L.; Baroni, S.; Car, R. Scuola Internazionale Superiore di Studi Avanzati , via Beirut 2/4, I-34014 Trieste Institut Romand de Recherche Numerique en Physique des Materiaux , PHB Ecublens, CH-1015 Lausanne )
1993-08-23
We report on the first successful attempt to apply the auxiliary-field quantum Monte Carlo technique to the calculation of ground-state properties of systems of many electrons interacting via a Coulomb potential. We have been able to substantially reduce the huge statistical fluctuations arising from the repulsive, long-range character of the interactions, which had so far hindered the application of this method to [ital realistic] Hamiltonians for atoms, molecules, and solids. Our technique is demonstrated with calculations of ground-state properties of the simplest molecular and solid-state systems, i.e., the H[sub 2] molecule and the homogeneous electron gas.
Criticality and long-range correlations in time series in classical and quantum systems.
Landa, E; Morales, Irving O; Fossion, R; Stránský, P; Velázquez, V; Vieyra, J C López; Frank, A
2011-07-01
We present arguments which indicate that a transitional state in between two different regimes implies the occurrence of 1/f time series and that this property is generic in both classical and quantum systems. Our study focuses on two particular examples: the one-dimensional module-1 logistic map and nuclear excitation spectra obtained with a schematic shell-model Hamiltonian. We suggest that a transitional point is characterized by the long-range correlations implied by 1/f time series. We apply a Fourier spectral analysis and the detrended fluctuation analysis method to study the fluctuations to each system. PMID:21867290
Criticality and long-range correlations in time series in classical and quantum systems
NASA Astrophysics Data System (ADS)
Landa, E.; Morales, Irving O.; Fossion, R.; Stránský, P.; Velázquez, V.; López Vieyra, J. C.; Frank, A.
2011-07-01
We present arguments which indicate that a transitional state in between two different regimes implies the occurrence of 1/f time series and that this property is generic in both classical and quantum systems. Our study focuses on two particular examples: the one-dimensional module-1 logistic map and nuclear excitation spectra obtained with a schematic shell-model Hamiltonian. We suggest that a transitional point is characterized by the long-range correlations implied by 1/f time series. We apply a Fourier spectral analysis and the detrended fluctuation analysis method to study the fluctuations to each system.
NASA Astrophysics Data System (ADS)
Ran, Ying; Jiang, Shenghan
Phases of matter are sharply defined in the thermodynamic limit. One major challenge of accurately simulating quantum phase diagrams of interacting quantum systems is due to the fact that numerical simulations usually deal with the energy density, a local property of quantum wavefunctions, while identifying different quantum phases generally rely on long-range physics. In this paper we construct generic fully symmetric quantum wavefunctions under certain assumptions using a type of tensor networks: projected entangled pair states, and provide practical simulation algorithms based on them. We find that quantum phases can be organized into crude classes distinguished by short-range physics, which is related to the fractionalization of both on-site symmetries and space-group symmetries. Consequently, our simulation algorithms, which are useful to study long-range physics as well, are expected to be able to sharply determine crude classes in interacting quantum systems efficiently. Examples of these crude classes are demonstrated in half-integer quantum spin systems on the kagome lattice. Limitations and generalizations of our results are discussed. The Alfred P. Sloan fellowship and National Science Foundation under Grant No. DMR-1151440.
Short-range interactions and scaling near integer quantum Hall transitions
Wang, Ziqiang; Fisher, Matthew P. A.; Girvin, S. M.; Chalker, J. T.
2000-03-15
We study the influence of short-range electron-electron interactions on scaling behavior near the integer quantum Hall plateau transitions. Short-range interactions are known to be irrelevant at the renormalization group fixed point which represents the transition in the noninteracting system. We find, nevertheless, that transport properties change discontinuously when interactions are introduced. Most importantly, in the thermodynamic limit the conductivity at finite temperature is zero without interactions, but nonzero in the presence of arbitrarily weak interactions. In addition, scaling as a function of frequency {omega} and temperature T is determined by the scaling variable {omega}/T{sup p} (where p is the exponent for the temperature dependence of the inelastic scattering rate) and not by {omega}/T, as it would be at a conventional quantum phase transition described by an interacting fixed point. We express the inelastic exponent p and the thermal exponent z{sub T} in terms of the scaling dimension -{alpha}<0 of the interaction strength and the dynamical exponent z (which has the value z=2), obtaining p=1+2{alpha}/z and z{sub T}=2/p. (c) 2000 The American Physical Society.
Entanglement and quantum-classical crossover in the extended XX model with long-range interactions
NASA Astrophysics Data System (ADS)
Campelo, M. W. V.; de Lima, J. P.; Gonçalves, L. L.
2013-02-01
In this work we considered the one-dimensional extended isotropic XY model (s=1/2) in a transverse field with uniform long-range interactions among the z components of the spins. We studied the classical critical behaviour of the model through the behaviour of the magnetization, isothermal susceptibility, internal energy and specific heat. We have obtained exact expressions for these functions and evaluated the critical exponents. The phase diagrams for the classical critical behaviour were built for three cases of the multiplicity p of the multiple spin interaction, namely p=2, p=3 and p→∞. We have also shown that the quantum phase transitions can also be characterized through two quantifiers of entanglement, namely, the concurrence and the von Neumann entropy. We have also verified through the von Neumann entropy how the central charge of the model is affected by the multiplicity p, the coupling exchange J2 and the uniform long-range interaction I.
Kaleidoscope of quantum phases in a long-range interacting spin-1 chain
NASA Astrophysics Data System (ADS)
Gong, Z.-X.; Maghrebi, M. Â. F.; Hu, A.; Foss-Feig, M.; Richerme, P.; Monroe, C.; Gorshkov, A. Â. V.
2016-05-01
Motivated directly by recent trapped-ion quantum simulation experiments, we carry out a comprehensive study of the phase diagram of a spin-1 chain with XXZ-type interactions that decay as 1 /rα , using a combination of finite and infinite-size DMRG calculations, spin-wave analysis, and field theory. In the absence of long-range interactions, varying the spin-coupling anisotropy leads to four distinct and well-studied phases: a ferromagnetic Ising phase, a disordered XY phase, a topological Haldane phase, and an antiferromagnetic Ising phase. If long-range interactions are antiferromagnetic and thus frustrated, we find primarily a quantitative change of the phase boundaries. On the other hand, ferromagnetic (nonfrustrated) long-range interactions qualitatively impact the entire phase diagram. Importantly, for α ≲3 , long-range interactions destroy the Haldane phase, break the conformal symmetry of the XY phase, give rise to a new phase that spontaneously breaks a U (1 ) continuous symmetry, and introduce a possibly exotic tricritical point with no direct parallel in short-range interacting spin chains. Importantly, we show that the main signatures of all five phases found could be observed experimentally in the near future.
Long-range energy transfer in self-assembled quantum dot-DNA cascades
NASA Astrophysics Data System (ADS)
Goodman, Samuel M.; Siu, Albert; Singh, Vivek; Nagpal, Prashant
2015-11-01
The size-dependent energy bandgaps of semiconductor nanocrystals or quantum dots (QDs) can be utilized in converting broadband incident radiation efficiently into electric current by cascade energy transfer (ET) between layers of different sized quantum dots, followed by charge dissociation and transport in the bottom layer. Self-assembling such cascade structures with angstrom-scale spatial precision is important for building realistic devices, and DNA-based QD self-assembly can provide an important alternative. Here we show long-range Dexter energy transfer in QD-DNA self-assembled single constructs and ensemble devices. Using photoluminescence, scanning tunneling spectroscopy, current-sensing AFM measurements in single QD-DNA cascade constructs, and temperature-dependent ensemble devices using TiO2 nanotubes, we show that Dexter energy transfer, likely mediated by the exciton-shelves formed in these QD-DNA self-assembled structures, can be used for efficient transport of energy across QD-DNA thin films.The size-dependent energy bandgaps of semiconductor nanocrystals or quantum dots (QDs) can be utilized in converting broadband incident radiation efficiently into electric current by cascade energy transfer (ET) between layers of different sized quantum dots, followed by charge dissociation and transport in the bottom layer. Self-assembling such cascade structures with angstrom-scale spatial precision is important for building realistic devices, and DNA-based QD self-assembly can provide an important alternative. Here we show long-range Dexter energy transfer in QD-DNA self-assembled single constructs and ensemble devices. Using photoluminescence, scanning tunneling spectroscopy, current-sensing AFM measurements in single QD-DNA cascade constructs, and temperature-dependent ensemble devices using TiO2 nanotubes, we show that Dexter energy transfer, likely mediated by the exciton-shelves formed in these QD-DNA self-assembled structures, can be used for efficient
Colavita, E.; Hacyan, S.
2014-03-15
We analyze the solutions of the Klein–Gordon and Dirac equations describing a charged particle in an electromagnetic plane wave combined with a magnetic field parallel to the direction of propagation of the wave. It is shown that the Klein–Gordon equation admits coherent states as solutions, while the corresponding solutions of the Dirac equation are superpositions of coherent and displaced-number states. Particular attention is paid to the resonant case in which the motion of the particle is unbounded. -- Highlights: •We study a relativistic electron in a particular electromagnetic field configuration. •New exact solutions of the Klein–Gordon and Dirac equations are obtained. •Coherent and displaced number states can describe a relativistic particle.
Relativistically strong electromagnetic radiation in a plasma
NASA Astrophysics Data System (ADS)
Bulanov, S. V.; Esirkepov, T. Zh.; Kando, M.; Kiriyama, H.; Kondo, K.
2016-03-01
Physical processes in a plasma under the action of relativistically strong electromagnetic waves generated by high-power lasers have been briefly reviewed. These processes are of interest in view of the development of new methods for acceleration of charged particles, creation of sources of bright hard electromagnetic radiation, and investigation of macroscopic quantum-electrodynamical processes. Attention is focused on nonlinear waves in a laser plasma for the creation of compact electron accelerators. The acceleration of plasma bunches by the radiation pressure of light is the most efficient regime of ion acceleration. Coherent hard electromagnetic radiation in the relativistic plasma is generated in the form of higher harmonics and/or electromagnetic pulses, which are compressed and intensified after reflection from relativistic mirrors created by nonlinear waves. In the limit of extremely strong electromagnetic waves, radiation friction, which accompanies the conversion of radiation from the optical range to the gamma range, fundamentally changes the behavior of the plasma. This process is accompanied by the production of electron-positron pairs, which is described within quantum electrodynamics theory.
Coester, F.
1985-01-01
A review is presented of three distinct approaches to the construction of relativistic dynamical models: (1) Relativistic canonical quantum mechanics. (The Hilbert space of states is independent of the interactions, which are introduced by modifying the energy operator.) (2) Hilbert spaces of manifestly covariant wave functions. (The interactions modify the metric of the Hilbert space.) (3) Covariant Green functions. In each of the three approaches the focus is on the formulation of the two-body dynamics, and problems in the construction of the corresponding many-body dynamics are discussed briefly. 21 refs.
Long-range energy transfer in self-assembled quantum dot-DNA cascades.
Goodman, Samuel M; Siu, Albert; Singh, Vivek; Nagpal, Prashant
2015-11-28
The size-dependent energy bandgaps of semiconductor nanocrystals or quantum dots (QDs) can be utilized in converting broadband incident radiation efficiently into electric current by cascade energy transfer (ET) between layers of different sized quantum dots, followed by charge dissociation and transport in the bottom layer. Self-assembling such cascade structures with angstrom-scale spatial precision is important for building realistic devices, and DNA-based QD self-assembly can provide an important alternative. Here we show long-range Dexter energy transfer in QD-DNA self-assembled single constructs and ensemble devices. Using photoluminescence, scanning tunneling spectroscopy, current-sensing AFM measurements in single QD-DNA cascade constructs, and temperature-dependent ensemble devices using TiO2 nanotubes, we show that Dexter energy transfer, likely mediated by the exciton-shelves formed in these QD-DNA self-assembled structures, can be used for efficient transport of energy across QD-DNA thin films. PMID:26498166
Optical properties of potential-inserted quantum wells in the near infrared and Terahertz ranges
NASA Astrophysics Data System (ADS)
Raouafi, F.; Samti, R.; Benchamekh, R.; Heyd, R.; Boyer-Richard, S.; Voisin, P.; Jancu, J.-M.
2016-06-01
We propose an engineering of the optical properties of GaAs/AlGaAs quantum wells using AlAs and InAs monolayer insertions. A quantitative study of the effects of the monolayer position and the well thickness on the interband and intersubband transitions, based on the extended-basis sp3d5s* tight-binding model, is presented. The effect of insertion on the interband transitions is compared with existing experimental data. As for intersubband transitions, we show that in a GaAs/AlGaAs quantum well including two AlAs and one InAs insertions, a three level {e1 ,e2 ,e3 } system where the transition energy e3 -e2 is lower and the transition energy e2 -e1 larger than the longitudinal optical phonon energy (36 meV) can be engineered together with a e3 -e2 transition energy widely tunable through the TeraHertz range.
Superconducting quantum magnetometer for the range 1-200/sup 0/K
Khlyustikov, I.N.
1985-06-01
A description is given of a superconducting quantum magnetometer for the range 1-200/sup 0/K. The receiving coil in the lead superconducting flux transformer is thermally insulated from the heated specimen by a high-vacuum gap. The temperature of the specimen is controlled by a manganin wire heater, while that of the magnetometric part of the instrument is kept at about 2/sup 0/K. This method of varying the specimen temperture enables one to measure the part of the magnetic moment of the specimen that is nonlinearly dependent on the field and temperature, and also to measure the field-independent part of the susceptibility as a function of temperature with a sensitivity in the magnetometer of about 10/sup -17/ Wb.
Higher rank numerical ranges and low rank perturbations of quantum channels
NASA Astrophysics Data System (ADS)
Li, Chi-Kwong; Poon, Yiu-Tung; Sze, Nung-Sing
2008-12-01
For a positive integer k, the rank-k numerical range [Lambda]k(A) of an operator A acting on a Hilbert space of dimension at least k is the set of scalars [lambda] such that PAP=[lambda]P for some rank k orthogonal projection P. In this paper, a close connection between low rank perturbation of an operator A and [Lambda]k(A) is established. In particular, for 1[less-than-or-equals, slant]r
Relativistic Electron-Electron Bremsstrahlung in Fusion Plasma
NASA Astrophysics Data System (ADS)
Chen, Wen-Jia; Kawai, Norio; Kawamura, Takaichi; Maegauchi, Tetsuo; Narumi, Hajime
1982-05-01
Transition matrices and differential cross sections for electron-electron bremsstrahlung in relativistic energy region are calculated by the lowest-order perturbation theory of quantum electrodynamics. The bremsstrahlung spectra and emission rates are evaluated for relativistic Maxwellian plasma. The results are discussed in comparison with those obtained by non-relativistic and extreme-relativistic approximations and it is noted that the relativistic effect becomes appreciable above the order of 10 keV for the electron temperature.