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In choosing a family of histories for a system, it is often convenient to choose a succession of locations in phase space, rather than configuration space, for comparison to classical histories. Although there are no good projections onto…

General Relativity and Quantum Cosmology · Physics 2008-02-03 Todd A. Brun

We consider the decoherence of phase space histories in a class of quantum Brownian motion models, consisting of a particle moving in a potential $V(x)$ in interaction with a heat bath at temperature $T$ and dissipation gamma, in the…

Quantum Physics · Physics 2009-10-28 C. Anastopoulos

This is a pedagogical paper where we present a physically motivated approach to introduce the coherent states of a harmonic oscillator from which it is simple to rigorously derive their mathematical definition. We do this in two different…

Quantum Physics · Physics 2024-10-23 Juan Pablo Paz , Augusto J. Roncaglia

Recent results on the decoherent histories quantization of simple cosmological models (minisuperspace models) are described. The most important issue is the construction, from the wave function, of a probability distribution answering…

General Relativity and Quantum Cosmology · Physics 2015-05-30 J. J. Halliwell

This paper explores the possibility that an exactly decoherent set of histories may be constructed from an approximately decoherent set by small distortions of the operators characterizing the histories. In particular, for the case of…

Quantum Physics · Physics 2009-11-06 J. J. Halliwell

Inspired by quantum cosmology, in which the wave function of the universe is annihilated by the total Hamiltonian, we consider the internal dynamics of a simple particle system in an energy eigenstate. Such a system does not possess a…

General Relativity and Quantum Cosmology · Physics 2009-11-07 J. J. Halliwell , J. Thorwart

We revisit the problem of the deformed oscillator with position-dependent mass [da Costa et al., J. Math. Phys. {\bf 62}, 092101 (2021)] in the classical and quantum formalisms, by introducing the effect of the mass function in both kinetic…

Quantum Physics · Physics 2023-02-07 Bruno G. da Costa , Ignacio S. Gomez , Biswanath Rath

In the quantization of simple cosmological models (minisuperspace models) described by the Wheeler-DeWitt equation, an important step is the construction, from the wave function, of a probability distribution answering various questions of…

General Relativity and Quantum Cosmology · Physics 2010-04-30 J. J. Halliwell

A comparison of classical and quantum evolution usually involves a quasi-probability distribution as a quantum analogue of the classical phase space distribution. In an alternate approach that we adopt here, the classical density is…

Chaotic Dynamics · Physics 2009-11-10 Debabrata Biswas

Nonlinear quantum optical systems are of paramount relevance for modern quantum technologies, as well as for the study of dissipative phase transitions. Their nonlinear nature makes their theoretical study very challenging and hence they…

Quantum Physics · Physics 2015-06-03 Peter Degenfeld-Schonburg , Carlos Navarrete-Benlloch , Michael J. Hartmann

We study the time evolution of a PT-symmetric, non-Hermitian quantum system for which the associated phase space is compact. We focus on the simplest non-trivial example of such a Hamiltonian, which is linear in the angular momentum…

Quantum Physics · Physics 2021-08-18 Iván F. Valtierra , Mario Gaeta , Adrian Ortega , Thomas Gorin

We consider two technical developments of the formalism of continuous-time histories. First, we provide an explicit description of histories of the simple harmonic oscillator on the classical histories phase space, comparing and contrasting…

Quantum Physics · Physics 2008-11-26 Aidan Burch

We discuss the case of histories labelled by a continuous time parameter in the {\em History Projection Operator} consistent-histories quantum theory. We describe how the appropriate representation of the history algebra may be chosen by…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Konstantina Savvidou

We propose a new point of view regarding the problem of time in quantum mechanics, based on the idea of replacing the usual time operator $\mathbf{T}$ with a suitable real-valued function $T$ on the space of physical states. The proper…

Unique set of coherent states for the anharmonic oscillator is obtained by requiring i. under the quantum mechanical time evolution a coherent state evolves into another, governed by trajectory in the classical phase space (of a related…

Quantum Physics · Physics 2007-05-23 H. S. Sharatchandra

The ongoing discussion whether thermodynamic properties can be extracted from a (possibly approximate) quantum mechanical time evolution using time averages is fed with an instructive example. It is shown for the harmonic oscillator how the…

Statistical Mechanics · Physics 2009-10-31 J. Schnack

By analyzing a paradigmatic example of the theory of dissipative systems -- the classical and quantum dissipative standard map -- we are able to explain the main features of the decay to the quantum equilibrium state. The classical…

Quantum Physics · Physics 2017-09-13 Gabriel G. Carlo , Leonardo Ermann , Alejandro M. F. Rivas , María E. Spina

It is of interest in a variety of contexts, and in particular in the arrival time problem, to consider the quantum state obtained through unitary evolution of an initial state regularly interspersed with periodic projections onto the…

Quantum Physics · Physics 2015-05-19 J. J. Halliwell , J. M. Yearsley

The ``problem of time'' has been a pressing issue in quantum gravity for some time. To help understand this problem, Rovelli proposed a model of a two harmonic oscillators system where one of the oscillators can be thought of as a ``clock''…

Quantum Physics · Physics 2009-10-30 M. C. Ashworth

In the first part of this paper the general perspective of history quantum theories is reviewed. History quantum theories provide a conceptual and mathematical framework for formulating quantum theories without a globally defined…

Mathematical Physics · Physics 2007-05-23 Oliver Rudolph
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