Showing papers on "Open quantum system published in 1982"
TL;DR: In this article, a recent proposal to achieve faster-than-light communication by means of an EPR-type experimental set-up is examined, and it is shown that such superluminal communication is not possible.
1,204 citations
TL;DR: In this article, the authors present a number of axioms that the asymptotic Green functions should obey in any reasonable theory of quantum gravity, except for one axiom, that of completeness.
Abstract: Quantum gravity seems to introduce a new level of unpredictability into physics over and above that normally associated with the uncertainty principle. This is because the metric of spacetime can fluctuate from being globally hyperbolic. In other words, the evolution is not completely determined by Cauchy data at past or future infinity. I present a number of axioms that the asymptotic Green functions should obey in any reasonable theory of quantum gravity. These axioms are the same as for ordinary quantum field theory in flat spacetime, except that one axiom, that of asymptotic completeness, is omitted. This allows pure quantum states to decay into mixed states. Calculations with simple models of topologically non-trivial spacetime indicate that such loss of quantum coherence will occur but that the effect will be very small except for fundamental scalar particles, if any such exist.
497 citations
TL;DR: In this paper, quantum mechanical Hamiltonian models of Turing machines are constructed on a finite lattice of spin-textonehalf{} systems, and they operate at the quantum limit in that the system (energy uncertainty)/(computation speed) is close to the limit given by the time-energy uncertainty principle.
Abstract: Quantum mechanical Hamiltonian models of Turing machines are constructed here on a finite lattice of spin-\textonehalf{} systems. The models do not dissipate any energy and they operate at the quantum limit in that the system (energy uncertainty)/(computation speed) is close to the limit given by the time-energy uncertainty principle.
273 citations
TL;DR: In this article, it was proved that under any time-periodic Hamiltonian, a nonresonant, bounded quantum system will reassemble itself infinitely often in the course of time.
Abstract: It is proved that under any time-periodic Hamiltonian, a nonresonant, bounded quantum system will reassemble itself infinitely often in the course of time. To illustrate these results computer experiments are performed on both a pulsed quantum rotor and an electron in the field of periodic electromagnetic pulses.
138 citations
TL;DR: In this paper, the spectral theory of many-body Schrodinger operators was developed and the geometric methods in the spectral analysis of the theory were developed, and it was shown that there are no very negative ions in Quantum Mechanics.
Abstract: In this paper we develop the geometric methods in the spectral theory of many-body Schrodinger operators. We give different simplified proofs of many of the basic results of the theory. We prove that there are no very negative ions in Quantum Mechanics.
128 citations
TL;DR: In this article, it was shown that the problem of quantum theory not being able to completely describe the measurement process is not a flaw of the theory but a logical necessity which is analogous to Godel's undecidability theorem.
Abstract: Quantum theory has been criticized for not being deterministic and therefore not universal: it cannot completely describe a measurement aimed at verifying its predictions (although any given apparatus can be considered as a quantum system). We investigate the possible alternatives. Theories where the observed world is deterministic but the observer is not (whatever the reason for that) lead to Bell’s nonseparability theorem. If, on the other hand, the observer too is deterministic, the theory is not verifiable. It follows that quantum theory must be the logically preferred option. Its inability to completely describe the measurement process appears to be not a flaw of the theory but a logical necessity which is analogous to Godel’s undecidability theorem.
95 citations
01 Jan 1982
TL;DR: In this paper, it was shown that 4, 4gren
Abstract: Quantum field theory (QFT) I would here like to understand as four-dimensional (mostly, Euclidean) continuum theory. Unfortunately, concerning this there are so far only negative rigorous results: 4, 04gren< cons t CI~. a) In ~4 b) An important recent result: In lattice approximation to #4 ~cannot have, in the 4' massless case, an anomalous infrared (IR) dimension (i.e., ~= O), and in the continuum limit, ~ cannot ha~e an anomalous ultraviolet (UV) dimension (which would also be given bye) f2~. This result explains the failure of all attempts so far to obtain 4 a nonzero ~ for ~4 by expansions,~ e.g. analytically: £-expansion in 4-~ dimen2 sions, I/N-expansion in (~L )4 theory, and numerically: strong-coupling expansion in ~__~ lattice theory~ f37. The strong-coupling-expansion result ~4~ that gren ~ O as ~Q~¢~ (~= correlation length, a = lattice constant)still remains to be proven rigorously.
88 citations
01 Jan 1982
TL;DR: In this paper, the Hamilton-Jacobi formalism for particle dynamics is extended to the case of directly interacting relativistic particles, and the Hamiltonian Hamiltonian mechanics of particle interactions is defined.
Abstract: 2-particle interactions produced by transformations of phase space.- Translation, dilation, Lorentz invariant two-particle interactions.- Spontaneous predictivisation.- Forms of relativistic quantum dynamics.- Relativistic-particle quantum mechanics.- The multitime covariant formalism of relativistic dynamics.- Second quantization of directly interacting particles.- The origins of predictive relativistic mechanics.- Singular lagrangian formalism in particle dynamics, I.- Singular lagrangian formalism in particle dynamics, II.- The Hamilton-Jacobi formalism for systems with constraints.- Constraint relativistic canonical particle dynamics.- Constraint Hamiltonian mechanics of directly interacting relativistic particles.
TL;DR: In this article, the importance of generalized quantum measurements in quantum optics and precision measurements is indicated, and an uncertainty relation more stringent than the usual one is derived for these measurements is derived, which can often be interpreted as approximate simultaneous measurements of noncommuting observables.
TL;DR: In this paper, the authors discuss the Aharonov-Bohm effect in terms of the trajectory interpretation of the quantum theory introduced by one of us (DB) and show that the fringe shift is explained as arising from the quantum potential.
Abstract: We discuss the Aharonov-Bohm effect in terms of the trajectory interpretation of the quantum theory introduced by one of us (DB) and show that the fringe shift is explained as arising from the quantum potential. The role of the vector potential is that of an intermediary which connects the quantum potential to the flux line in a localizable way. This approach is seen to provide further insight into the meaning of the AB effect, by making possible a visualizable representation of how the slit system produces the interference pattern and how this pattern is affected by the flux line.
TL;DR: In this article, a path-integral representation for coherent state propagators is presented and evaluated for general single-mode and multimode Hamiltonians, which are at most quadratic in the creation and destruction operators of the field.
Abstract: A formalism for applying path integrals to certain problems in nonlinear optics is considered. The properties of a coherent-state propagator are discussed and a path-integral representation for the propagator is presented. This representation is then employed in evaluating the propagator for general single-mode and multimode Hamiltonians which are at most quadratic in the creation and destruction operators of the field. Some examples involving parametric processes are given.
TL;DR: In this article, a phenomenological theory of stochastic quantum mechanics is presented, followed by a list of its main results and perspectives, and a possible answer to the question about the origin of quantum mechanics by assigning a real character to the vacuum radiation field is given.
Abstract: Arguments are given in favor of a stochastic theory of quantum mechanics, clearly distinguishable from Brownian motion theory. A brief exposition of the phenomenological theory of stochastic quantum mechanics is presented, followed by a list of its main results and perspectives. A possible answer to the question about the origin of stochasticity is given in stochastic electrodynamics by assigning a real character to the vacuum radiation field. This theory is shown to reproduce important quantum mechanical results, some of which are presented explicitly to illustrate its potentialities. Finally the main problems and some perspectives of research within stochastic electrodynamics are discussed.
TL;DR: In this article, it is shown that the evolution of a quantum system can be considered as a parallel transport of unitary operators in Hilbert spaces along the time with respect to a generalized connection, and the different quantum representations of the system are shown to correspond to the choices of cross sections in the principal fiber bundle where the generalized connection is defined.
Abstract: We point out that the evolution of a quantum system can be considered as a parallel transport of unitary operators in Hilbert spaces along the time with respect to a generalized connection. The different quantum representations of the system are shown to correspond to the choices of cross sections in the principal fiber bundle where the generalized connection is defined. This interpre‐ tation of time evolution allows us to solve the problem of the formulation of the evolution of a quantum particle in a four‐dimensional gauge field.
TL;DR: In this article, it was shown that the equilibrium states are exactly the states invariant under adiabatic local perturbations, and the relevance of this fact to the problem of ergodicity was discussed.
Abstract: We show that with suitable assumptions the equilibrium states are exactly the states invariant under adiabatic local perturbations. The relevance of this fact to the problem of ergodicity is discussed.
TL;DR: In this article, a micro realistic, propensity version of quantum theory is proposed, according to which fundamental physical entities have physical characteristics which determine probabilistically how they interact with one another (rather than with measuring instruments).
Abstract: A fully micro realistic, propensity version of quantum theory is proposed, according to which fundamental physical entities—neither particles nor fields—have physical characteristics which determine probabilistically how they interact with one another (rather than with measuring instruments) The version of quantum “smearon” theory proposed here does not modify the equations of orthodox quantum theory: rather it gives a radically new interpretation to these equations It is argued that (i) there are strong general reasons for preferrring quantum “smearon” theory to orthodox quantum theory; (ii) the proposed change in physical interpretation leads quantum “smearon” theory to make experimental predictions subtly different from those of orthodox quantum theory Some possible crucial experiments are considered
TL;DR: In this article, the problem of particle detection in unitary quantum mechanics and in ordinary quantum mechanics is simplified and reduced to finding the packet by means of a threshold device (called detector).
Abstract: The general approach to the theory of statistical measurements in any quantum theory is considered and is shown to contain great difficulties in particular cases. In unitary quantum mechanics a particle is represented by a periodically disappearing and reappearing wave packet, on which vacuum fluctuations are superimposed in some random way. Thus the problem of detecting a particle may be simplified and reduced to finding the packet by means of a threshold device (called detector). This problem is solved in the most general case. It is shown that the optimal detector (which minimizes the error) has to possess a threshold energy which is equal to one-fourth of the registered particle energy. The probabilities of particle detection in unitary quantum mechanics and in ordinary quantum mechanics are shown to be different by two orders of magnitude, which can be tested experimentally.
TL;DR: In this paper, a statistical problem on the detection of particles by macroinstruments in unitary quantum mechanics is considered. But the probability of particle detection is not shown to be different by two orders of magnitude, which can be tested experimentally.
Abstract: The paper is concerned with a statistical problem on the detection of particles by macroinstruments in unitary quantum mechanics. Requirements of macroinstruments whose error is minimal are defined. The wave function in unitary quantum mechanics is interpreted. The probabilities of particle detection in unitary quantum mechanics and in conventional quantum mechanics are shown to be different by two orders of magnitude, which can be tested experimentally.
TL;DR: In this article, it was shown that the laws of physics impose no fundamental bound on the rate at which information can be processed, and that quantum effects do not impose such fundamental bounds.
Abstract: It is shown that the laws of physics impose no fundamental bound on the rate at which information can be processed. Recent claims that quantum effects impose such bounds are discussed and shown to be erroneous.
TL;DR: It is proven that for a spinless particle constrained to move on a curve, a potential term proportional to the curvature square must be added to the Schrodinger equation as mentioned in this paper.
Abstract: It is proven that for a spinless particle, constrained to move on a curve, a potential term, proportional to the curvature square, must be added to the Schro-dinger equation.