Toward relaxation asymmetry: Heating is faster than cooling

An asymmetry in thermal relaxation toward equilibrium has been uncovered for Langevin systems near stable minima [Phys. Rev. Lett. 125, 110602 (2020)10.1103/PhysRevLett.125.110602]. It has been shown that, given the same degree of nonequilibrium of the initial distributions, relaxation from a lower...

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Main Authors: Tan Van Vu, Yoshihiko Hasegawa
Format: Article
Language:English
Published: American Physical Society 2021-12-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.3.043160
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author Tan Van Vu
Yoshihiko Hasegawa
author_facet Tan Van Vu
Yoshihiko Hasegawa
author_sort Tan Van Vu
collection DOAJ
description An asymmetry in thermal relaxation toward equilibrium has been uncovered for Langevin systems near stable minima [Phys. Rev. Lett. 125, 110602 (2020)10.1103/PhysRevLett.125.110602]. It has been shown that, given the same degree of nonequilibrium of the initial distributions, relaxation from a lower temperature state (heating) is faster than that from a higher temperature state (cooling). In this paper, we elucidate this relaxation asymmetry for discrete-state Markovian systems described by the master equation. We rigorously prove that heating is faster than cooling for arbitrary two-state systems, whereas for systems with more than two distinct energy levels, the relaxation asymmetry is no longer universal. Furthermore, for systems whose energy levels degenerate into two energy states, we find that there exist critical thresholds of the energy gap. Depending on the magnitude of the energy gap, heating can be faster or slower than cooling, irrespective of the transition rates between states. Our results clarify the relaxation asymmetry for discrete-state systems and reveal several hidden features inherent in thermal relaxation.
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spelling doaj.art-0341bef3c12b4c438000be82c9cbd2852024-04-12T17:16:07ZengAmerican Physical SocietyPhysical Review Research2643-15642021-12-013404316010.1103/PhysRevResearch.3.043160Toward relaxation asymmetry: Heating is faster than coolingTan Van VuYoshihiko HasegawaAn asymmetry in thermal relaxation toward equilibrium has been uncovered for Langevin systems near stable minima [Phys. Rev. Lett. 125, 110602 (2020)10.1103/PhysRevLett.125.110602]. It has been shown that, given the same degree of nonequilibrium of the initial distributions, relaxation from a lower temperature state (heating) is faster than that from a higher temperature state (cooling). In this paper, we elucidate this relaxation asymmetry for discrete-state Markovian systems described by the master equation. We rigorously prove that heating is faster than cooling for arbitrary two-state systems, whereas for systems with more than two distinct energy levels, the relaxation asymmetry is no longer universal. Furthermore, for systems whose energy levels degenerate into two energy states, we find that there exist critical thresholds of the energy gap. Depending on the magnitude of the energy gap, heating can be faster or slower than cooling, irrespective of the transition rates between states. Our results clarify the relaxation asymmetry for discrete-state systems and reveal several hidden features inherent in thermal relaxation.http://doi.org/10.1103/PhysRevResearch.3.043160
spellingShingle Tan Van Vu
Yoshihiko Hasegawa
Toward relaxation asymmetry: Heating is faster than cooling
Physical Review Research
title Toward relaxation asymmetry: Heating is faster than cooling
title_full Toward relaxation asymmetry: Heating is faster than cooling
title_fullStr Toward relaxation asymmetry: Heating is faster than cooling
title_full_unstemmed Toward relaxation asymmetry: Heating is faster than cooling
title_short Toward relaxation asymmetry: Heating is faster than cooling
title_sort toward relaxation asymmetry heating is faster than cooling
url http://doi.org/10.1103/PhysRevResearch.3.043160
work_keys_str_mv AT tanvanvu towardrelaxationasymmetryheatingisfasterthancooling
AT yoshihikohasegawa towardrelaxationasymmetryheatingisfasterthancooling