Showing papers on "Open quantum system published in 1984"
Book•
29 Feb 1984
Abstract: The quantum statistical properties of radiation represent an important branch of modern physics with rapidly increasing applications in spectroscopy, quantum generators of radiation, optical communication, etc. They have also an increasing role in fields other than pure physics, such as biophysics, psychophysics, biology, etc. The present monograph represents an extension and continuation of the previous monograph of this author entitled Coherence of Light (Van Nostrand Reinhold Company, London 1972, translated into Russian in the Publishing House Mir, Moscow 1974) and of a review chapter in Progress in Optics, Vol. 18 (E. Wolf (Ed.), North-Holland Publishing Company, Amsterdam 1980), published just recently. It applies the fundamental tools of the coherent-state technique, as described in Coherence of Light, to particular studies of the quantum statistical properties of radiation in its interaction with matter. In particular, nonlinear optical processes are considered, and purely quantum phenomena such as antibunching of photons are discussed. This book will be useful to research workers in the fields of quantum optics and electronics, quantum generators, optical communication and solid-state physics, as well as to students of physics, optical engineering and opto-electronics.
588 citations
TL;DR: In this article, a modified Hamiltonian equation of motion for density matrices was proposed to interpret upper bounds on the violation of quantum mechanics in different... phenomenological situations.
389 citations
TL;DR: In this article, a general approach, within the framework of canonical quantization, is described for analyzing the quantum behavior of complicated electronic circuits, capable of generating squeezed-state or two-photon coherent-state signals.
Abstract: A general approach, within the framework of canonical quantization, is described for analyzing the quantum behavior of complicated electronic circuits. This approach is capable of dealing with electrical networks having nonlinear or dissipative elements. The techniques are applied to circuits capable of generating squeezed-state or two-photon coherent-state signals. Circuits capable of performing back-action-evading electrical measurements are also discussed.
375 citations
TL;DR: In this article, the quantum motion of a periodically kicked rotator is shown to be related to Anderson's problem of moving a quantum particle in a one-dimensional lattice in the presence of a static-random potential.
Abstract: The quantum motion of a periodically kicked rotator is shown to be related to Anderson's problem of motion of a quantum particle in a one-dimensional lattice in the presence of a static-random potential. Classically, the first problem is nonintegrable and, for certain values of the parameters, exhibits chaos and diffusion in phase space; in the second problem, diffusion takes place in configuration space. Quantum phase interference, however, is known to suppress diffusion in Anderson's problem and to produce quasiperiodic motion. By establishing a mapping between the two systems we show that a similar effect determines the dynamics of the quantum rotator. As a result its wave functions are localized in phase space and their time evolution is quasiperiodic. This result explains the quantum recurrences and boundedness of the energy found in recent numerical work.
316 citations
Book•
30 Nov 1984
TL;DR: Open quantum systems as mentioned in this paper are those that cannot be regarded as isolated from the rest of the physical universe, i.e. those that are not stable in the sense that they are not able to be modeled by a tensor product of the state Hilbert space of the open system and the isolated system.
Abstract: Every part of physics offers examples of non-stability phenomena, but probably nowhere are they so plentiful and worthy of study as in the realm of quantum theory. The present volume is devoted to this problem: we shall be concerned with open quantum systems, i.e. those that cannot be regarded as isolated from the rest of the physical universe. It is a natural framework in which non-stationary processes can be investigated. There are two main approaches to the treatment of open systems in quantum theory. In both the system under consideration is viewed as part of a larger system, assumed to be isolated in a reasonable approximation. They are differentiated mainly by the way in which the state Hilbert space of the open system is related to that of the isolated system - either by orthogonal sum or by tensor product. Though often applicable simultaneously to the same physical situation, these approaches are complementary in a sense and are adapted to different purposes. Here we shall be concerned with the first approach, which is suitable primarily for a description of decay processes, absorption, etc. The second approach is used mostly for the treatment of various relaxation phenomena. It is comparably better examined at present; in particular, the reader may consult a monograph by E. B. Davies.
204 citations
198 citations
TL;DR: The Gaussian effective potential (GEP) is a natural extension of intuitive notions familiar from quantum mechanics as discussed by the authors, and it has been used as a guide to quantum field theories.
Abstract: We advertise the virtues of the Gaussian effective potential (GEP) as a guide to the behavior of quantum field theories. Much superior to the usual one-loop effective potential, the GEP is a natural extension of intuitive notions familiar from quantum mechanics. A variety of quantum-mechanical examples are studied here, with an eye to field-theoretic analogies. Quantum restoration of symmetry, dynamical mass generation, and "quantum-mechanical resuscitation" are among the phenomena discussed. We suggest how the GEP could become the basis of a systematic approximation procedure. A companion paper will deal with scalar field theory.
142 citations
Book•
01 Jan 1984
TL;DR: In this article, basic and well-established concepts of particle physics for the autodidact who is curious about recent developments in fundamental physics are elucidated for the uninitiated.
Abstract: This volume elucidates basic and well-established concepts of particle physics for the autodidact who is curious about recent developments in fundamental physics. Elementary quantum mechanics is a background must. Contents, abridged: The evolution of the particle concept before the advent of quantum mechanics. Nonrelativistic quantum mechanics and atomic physics. Relativistic quantum theory. Nuclear phenomena. Subnuclear phenomena. Index.
117 citations
TL;DR: In this paper, the authors describe the evolution of a physical system as a unique actuality, in principle independent of any observer (so that they can, for example, provide a simple and coherent answer to the Schrodinger cat paradox).
Abstract: We review briefly the quantum potential approach to quantum theory, and show that it yields a completely consistent account of the measurement process, including especially what has been called the “collapse of the wave function.” This is done with the aid of a new concept of active information, which enables us to describe the evolution of a physical system as a unique actuality, in principle independent of any observer (so that we can, for example, provide a simple and coherent answer to the Schrodinger cat paradox). Finally, we extend this approach to relativistic quantum field theories, and show that it leads to results that are consistent with all the known experimental implications of the theory of relativity, despite the nonlocality which this approach entails.
Book•
14 Jun 1984
TL;DR: In this article, the metaphorical name of tunnelling is given to the process, possible in quantum mechanics, but not in classical mechanics, whereby a particle can disappear from one side of a potential energy barrier and appear on the other side without having enough kinetic energy to mount the barrier.
Abstract: ‘Tunnelling’ is the metaphorical name given to the process, possible in quantum mechanics, but not in classical mechanics, whereby a particle can disappear from one side of a potential-energy barrier and appear on the other side without having enough kinetic energy to mount the barrier. One can think of this as a manifestation of the wave-nature of particles. The wavelength is larger if a particle is lighter. In particular electrons, being very light compared to atoms, have wavelengths as large or larger than atoms at energies found in the valence shells of molecules. Thus, they easily ooze through and around atoms and molecules. We are also concerned with the tunnelling of heavy particles: nuclei, atoms, molecules.
TL;DR: In this paper, the authors compare the dynamics of quantum wave packets with those of classical trajectory ensembles via the Wigner transform and find that there is generally excellent classical-quantum correspondence except for certain specific cases of tunneling and interference.
Abstract: We compare the dynamics of quantum wave packets with the dynamics of classical trajectory ensembles. The wave packets are Gaussian with expectation values of position and momenta which centers them in phase space. The classical trajectory ensembles are generated directly from the quantum wave packets via the Wigner transform. Quantum and classical dynamics are then compared using several quantum measures and the analogous classical ones derived from the Wigner equivalent formalism. Comparisons are made for several model potentials and it is found that there is generally excellent classical–quantum correspondence except for certain specific cases of tunneling and interference. In general, this correspondence is also very good in regions of phase space where there is classical chaos.
TL;DR: In this article, the quantum statistics of linear and nonlinear optical Phenomena are presented. But they do not consider the non-linear optical properties of the optical components of the system.
Abstract: (1984). Quantum Statistics of Linear and Nonlinear Optical Phenomena. Optica Acta: International Journal of Optics: Vol. 31, No. 8, pp. 847-847.
01 Jan 1984
TL;DR: In this paper, the authors describe a new formalism for analyzing a particular class of nonlinear optical devices, called two-photon devices, which operate as follows: several modes of the electromagnetic field are coupled via a nonlinearity in some material; two of the modes are the device's "signal" modes, the rest are "pump" modes; photons are created or destroyed in the signal modes two at a time.
Abstract: In this paper we describe a new formalism for analyzing a particular class of nonlinear optical devices. We call these devices two-photon devices because they operate as follows: several modes of the electromagnetic field are coupled via a nonlinearity in some material; two of the modes are the device’s “signal” modes, the rest are “pump” modes; photons are created or destroyed in the signal modes two at a time. Examples include parametric amplifiers and four-wave mixers. Two-photon devices are to be contrasted with one-photon devices, such as the laser, in which photons are created or destroyed in the signal mode one at a time. The formalism used in one-photon optics uses variables and quantum states suited to describing the output of a one-photon device.
01 Jan 1984
TL;DR: In this article, a model of irreversible deterministic quantum dynamics is proposed for quantum dynamical semigroups and a hierarchy of mixing properties for non-commutative K-systems.
Abstract: Some trends and problems in quantum probability.- Scattering theory for quantum dynamical semigroups.- Quantum stochastic processes.- On dynamical semigroups and compact group actions.- Irreversibility and chaos in quantum systems.- Noncommutative integration and conditioning.- Stochastic representation of thermal functionals.- Statistical independence of local algebras.- On the problem of non configurational observables in stochastic mechanics.- Markovian limits of multi time correlation functions for open quantum systems.- On stationary markov dilations of quantum dynamical semigroups (some remarks inspired by the workshop).- A model of irreversible deterministic quantum dynamics.- Probability and quantum mechanics the conceptual foundations of stochastic mechanics.- Kolmogorovian statistical invariants for the aspect-rapisarda experiment.- Covariant measurements and imprimitivity systems.- Construction of quantum diffusions.- The analytic continuation of a osterwalder-schrader positive representation of the euclidean group to a representation of the poincare group.- Appendix: A connection between quantum systems and stochastic processes.- Extensions of gleason theorem.- Examples of markov dilations over the 2x2 matrices.- Hamiltonian models of classical and quantum stochastic processes.- Quantum entropy and irreversibility.- Quantum ergodic theorems.- The quantum measurement process and the observation of continuous trajectories.- Generalized transition probabilities and applications.- Some remarks on quantum logics and ordered vector spaces.- A hierarchy of mixing properties for non-commutative K-systems.- Type and normality properties of some infrared representations.- Quantum theory of continuous measurements.- On the implementability of certain positive maps.- Energy versus entropy balance arguments in classical lattice systems.- Ito solution of the linear quantum stochastic differential equation describing light emission and absorption.
TL;DR: The quantum theory of the two-level atom coupled to a single mode of the electromagnetic field is considered as a simple example of "quantum chaos" defined as the quantum behavior of a dynamical system which is non-integrable in the classical limit.
TL;DR: In this article, it is argued that a Born-Oppenheimer type approximation leads to dynamic potentials that make the nonobvious localization obvious, and applications are mentioned for photoselective chemistry, absorption spectroscopy, and chemical mechanisms.
Abstract: Coupled motion in many degrees of freedom is known to often show in classical mechanics unexpectedly localized quasiperiodic motion that could not have been anticipated from the potential function. Similar phenomena is observed in quantum theory and this article discusses the fundamental physics of such localization. It is argued below that a Born–Oppenheimer type approximation leads to dynamic potentials that make the nonobvious localization obvious. Applications are mentioned for photoselective chemistry, absorption spectroscopy, and chemical mechanisms.
TL;DR: In this paper, the authors give special attention to the notion that the quantum frequency spectrum of a periodic system reduces to the classical spectrum in this limit and show that the classical result is not always recovered in the limit of large quantum numbers.
Abstract: The correspondence principle addresses the connection between classical and quantum physics. The simple statement that quantum mechanics reduces to classical mechanics in the limit where the principal quantum number n approaches infinity, while found in many textbooks, is not true in general. In this article we will give special attention to the notion that the quantum frequency spectrum of a periodic system reduces to the classical spectrum in this limit. Two simple counter‐examples—a particle in a cubical box, and a rigid rotator—will show us that the classical result is not always recovered in the limit of large quantum numbers. The usual textbook formulation of Bohr's frequency correspondence principle does not apply to all periodic systems, and the limits n→∞ and h→0 are not universally equivalent.
TL;DR: The classical and quantum mechanical formalisms of the models were developed in this article and quantisation was done in such a way that the quantum theory can be represented explicitly in as simple a form as possible, and the problem of ordering of operators is resolved so as to maintain the supersymmetry algebra of the classical theory.
Abstract: The classical and quantum mechanical formalisms of the models are developed. The quantisation is done in such a way that the quantum theory can be represented explicitly in as simple a form as possible, and the problem of ordering of operators is resolved so as to maintain the supersymmetry algebra of the classical theory.
Book•
31 Oct 1984
TL;DR: In this article, the main approaches to this most accurate of all physical theories are discussed: the Hamiltonian approach, the Green's function approach with particular emphasis to bound state problems, and the newer, nonperturbative approach.
Abstract: The borderline of quantum electrodynamics and quantum optics offer spectacular results and problems concerning the foundations of radiation theory Perhaps the major new viewpoint that has emerged from recent investigations is that one can now work inside a time-dependent quantum process, whereas up to now all elementary quantum processes were either stationary, or one worked with asymptotic in-and out-states, ie an S-matrix approach In the-rirst part of this volume, the Quantum Electrodynamics, the present status of the main approaches to this most accurate of all physical theories are discussed: the Hamiltonian approach, the Green's function approach with particular emphasis to bound state problems, and the newer, nonperturbative approach The latest numerical results on radiative corrections, Lamb shifts and anomalous magnetic moments are reviewed with new results for high Z atoms Also discussed are different theoretical interpretations of the radiative phenomena as due to quantized field vacuum fluctuations or due to self energy A small group of contributions are devoted to the physics and mathematical description of decaying or unstable states in quantum theory This remarkable phenomenon of quantum theory still needs complete clarification, it is a time-dependent phenomenon, which can be described also by asymptotic S-matrix methods, but with complex energies
TL;DR: In this paper, the authors examined the concept of nodal breakup of wave functions as a criterion for quantum mechanical ergodicity and found that complex nodal structure of wave function is not sufficient to determine quantum mechanical eigenstate.
Abstract: We examine the concept of nodal breakup of wave functions as a criterion for quantum mechanical ergodicity. We find that complex nodal structure of wave functions is not sufficient to determine quantum mechanical ergodicity. The influence of classical resonances [which manifest themselves as classical resonance zones (CRZ)] may also be responsible for the seeming complexity of nodal structure. We quantify this by reexamining one of the two systems studied by Stratt, Handy, and Miller [J. Chem. Phys. 71, 3311 (1974)] from both a quantum mechanical and classical point of view. We conclude that quasiperiodic classical motion can account for highly distorted quantum eigenstates. One should always keep this in mind when addressing questions regarding quantum mechanical ergodicity.
01 Jan 1984
TL;DR: In this paper, the authors discuss the difficulties posed in Bohr's theory of atomic structure and in the radiation theory of light, and present the physically new viewpoints that distinguish quantum mechanics from classical physics.
Abstract: Quantum mechanics, on which I am to speak here, arose, in its formal content, from the endeavour to expand Bohr’s principle of correspondence to a complete mathematical scheme by refining his assertions. The physically new viewpoints that distinguish quantum mechanics from classical physics were prepared by the researches of various investigators engaged in analysing the difficulties posed in Bohr’s theory of atomic structure and in the radiation theory of light.
TL;DR: In this article, the physical interpretation of the one-dimensional quantum damped oscillator is analyzed from the viewpoint of group theory and it is shown how to transform the system into a quantum oscillator with variable frequency.
Abstract: The longstanding problem of the physical interpretation of the one-dimensional quantum damped oscillator is analysed here from the viewpoint of group theory. It is shown how to transform the system into a quantum oscillator with variable frequency. However, the main features of the final system are rather those of a simple stationary oscillator with 'renormalised' constant frequency. The quantum mechanical system cannot be at all interpreted as a 'dissipative' quantum system as has been claimed by some authors.
01 Jan 1984
TL;DR: In this paper, it was shown that Bell inequalities are satisfied iff the two physical systems are separated, whether the systems are quantum systems or classical systems is of no matter, and they gave an example of a classical macroscopical situation where Bell inequalities were violated.
Abstract: Since we were able to show recently that quantum mechanics can not describe separated physical systems we analyse again the reasoning of Einstein-Podolsky-Rosen, and find that the most straith forward conclusion of this paradox is not correct. We indicate the missing elements of reality in the quantum mechanical description of separated physical systems. We show that Bell inequalities are satisfied iff the two physical systems are separated, whether the systems are quantum systems or classical systems is of no matter. We give an example of a classical macroscopical situation where Bell inequalities are violated.
TL;DR: In this article, the classical and quantum mechanical formalisms of the model were developed and quantisation was performed in such a way that the quantum theory can be represented explicitly in as simple a form as possible, and the problem of ordering of operators was resolved so as to maintain the extended N=2 supersymmetry algebra of the classical theory.
Abstract: The classical and quantum mechanical formalisms of the model are developed. The quantisation is performed in such a way that the quantum theory can be represented explicitly in as simple a form as possible, and the problem of ordering of operators is resolved so as to maintain the extended N=2 supersymmetry algebra of the classical theory.
TL;DR: In this paper, a general concept of a phase-space representation of the ordinary Hilbert-space quantum theory is formulated, and then, by using some elementary facts of functional analysis, several equivalent forms of that concept are analyzed.
Abstract: In the present paper a general concept of a phase-space representation of the ordinary Hilbert-space quantum theory is formulated, and then, by using some elementary facts of functional analysis, several equivalent forms of that concept are analyzed. Several important physical examples are presented in Section 3 of the paper.