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Phase space localization and approach to thermal equilibrium for a class of open systems

Andreas Zoupas

arXiv:quant-ph/9512025Physics Letters AAug 1, 19962 citations

Statistical physics and phase transitions

Lorenza Saitta, Attilio Giordana, Antoine Cornuéjols

Cambridge University Press eBooksJun 16, 20110 citations

Spontaneous Solitons in the Thermal Equilibrium of a Quasi-1D Bose Gas

Tomasz Karpiuk, Piotr Deuar, Przemysław Bienias +5 more

We show that solitons occur generically in the thermal equilibrium state of a weakly interacting elongated Bose gas, without the need for external forcing or perturbations. This reveals a major new quality to the experimentally widespread quasicondensate state, usually thought of as primarily phase-fluctuating. Thermal solitons are seen in uniform 1D, trapped 1D, and elongated 3D gases, appearing as shallow solitons at low quasicondensate temperatures, becoming widespread and deep as temperature rises. This behavior can be understood via thermal occupation of the type II excitations in the Lieb-Liniger model of a uniform 1D gas. Furthermore, we find that the quasicondensate phase includes very appreciable density fluctuations while leaving phase fluctuations largely unaltered from the standard picture derived from a density-fluctuation-free treatment.We show that solitons occur generically in the thermal equilibrium state of a weakly interacting elongated Bose gas, without the need for external forcing or perturbations. This reveals a major new quality to the experimentally widespread quasicondensate state, usually thought of as primarily phase-fluctuating. Thermal solitons are seen in uniform 1D, trapped 1D, and elongated 3D gases, appearing as shallow solitons at low quasicondensate temperatures, becoming widespread and deep as temperature rises. This behavior can be understood via thermal occupation of the type II excitations in the Lieb-Liniger model of a uniform 1D gas. Furthermore, we find that the quasicondensate phase includes very appreciable density fluctuations while leaving phase fluctuations largely unaltered from the standard picture derived from a density-fluctuation-free treatment.

arXiv:1205.2363Physical Review LettersNov 13, 201246 citations

Random Hamiltonian in thermal equilibrium

Dorje C. Brody, David C P Ellis, Darryl D. Holm

A framework for the investigation of disordered quantum systems in thermal equilibrium is proposed. The approach is based on a dynamical model—which consists of a combination of a double-bracket gradient flow and a uniform Brownian fluctuation—that 'equilibrates' the Hamiltonian into a canonical distribution. The resulting equilibrium state is used to calculate quenched and annealed averages of quantum observables.

arXiv:0901.2025Journal of Physics Conference SeriesJun 1, 20092 citations

Non-Equilibrium Phase Transitions

Malte Henkel, Haye Hinrichsen, Sven Lübeck

Theoretical and mathematical physicsJan 1, 2008281 citations

Heat exchange and fluctuation in Gaussian thermal states in the quantum realm

A. R. Usha Devi, Sudha, A. K. Rajagopal +1 more

Abstract The celebrated exchange fluctuation theorem—proposed by Jarzynski and Wójcik (2004 Phys. Rev. Lett. 92 230602) for heat exchange between two systems in thermal equilibrium at different temperatures—is explored here for quantum Gaussian states in thermal equilibrium. We employ the Wigner distribution function formalism for quantum states, which exhibits a close resemblance to the classical phase-space trajectory description, to arrive at a formal Jarzynski–Wójcik result. For two Gaussian states in thermal equilibrium at two different temperatures kept in contact with each other for a fixed duration of time, we show that the Jarzynski–Wójcik- like relation reduces to the corresponding classical result in the limit ℏ → 0.Abstract The celebrated exchange fluctuation theorem—proposed by Jarzynski and Wójcik (2004 Phys. Rev. Lett. 92 230602) for heat exchange between two systems in thermal equilibrium at different temperatures—is explored here for quantum Gaussian states in thermal equilibrium. We employ the Wigner distribution function formalism for quantum states, which exhibits a close resemblance to the classical phase-space trajectory description, to arrive at a formal Jarzynski–Wójcik result. For two Gaussian states in thermal equilibrium at two different temperatures kept in contact with each other for a fixed duration of time, we show that the Jarzynski–Wójcik- like relation reduces to the corresponding classical result in the limit ℏ → 0.

arXiv:2007.04255Journal of Statistical Mechanics Theory and ExperimentFeb 1, 20210 citations

Uniformity of the phase space and fluctuations in thermal equilibrium

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