Emergence of distinct relaxation behaviour and Quantum Regression Theorem in the Ultra-strong Coupling Limit

Fuente: arXiv
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Main Authors: Khan, Sakil, Agarwalla, Bijay Kumar
Format: Preprint
Published: 2025
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author Khan, Sakil
Agarwalla, Bijay Kumar
author_facet Khan, Sakil
Agarwalla, Bijay Kumar
contents In the framework of open quantum systems, we derive the dynamical equation governing two-time correlation functions in the ultra-strong coupling (USC) regime between the system and its environment. Unlike the case of the standard weak-coupling regime, in the USC case, we find distinct relaxation behavior for two-time correlators depending on the types of the operators involved in the correlation function. Interestingly, the Quantum Regression Theorem (QRT) emerges after the fastest relaxation time-scale, which is governed by the system-bath coupling strength. We exemplify our findings for the dissipative spin-boson model and further find excellent agreement with the numerically exact hierarchical equations of motion (HEOM) method.
format Preprint
id arxiv_https___arxiv_org_abs_2508_08378
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Emergence of distinct relaxation behaviour and Quantum Regression Theorem in the Ultra-strong Coupling Limit
Khan, Sakil
Agarwalla, Bijay Kumar
Statistical Mechanics
Mesoscale and Nanoscale Physics
High Energy Physics - Theory
Quantum Physics
In the framework of open quantum systems, we derive the dynamical equation governing two-time correlation functions in the ultra-strong coupling (USC) regime between the system and its environment. Unlike the case of the standard weak-coupling regime, in the USC case, we find distinct relaxation behavior for two-time correlators depending on the types of the operators involved in the correlation function. Interestingly, the Quantum Regression Theorem (QRT) emerges after the fastest relaxation time-scale, which is governed by the system-bath coupling strength. We exemplify our findings for the dissipative spin-boson model and further find excellent agreement with the numerically exact hierarchical equations of motion (HEOM) method.
title Emergence of distinct relaxation behaviour and Quantum Regression Theorem in the Ultra-strong Coupling Limit
topic Statistical Mechanics
Mesoscale and Nanoscale Physics
High Energy Physics - Theory
Quantum Physics
url https://arxiv.org/abs/2508.08378