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Main Authors: Guo, Chu, Wu, Wei, Xu, Xiansong, Jiang, Tian, Chen, Ping-Xing, Chen, Ruofan
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.01556
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author Guo, Chu
Wu, Wei
Xu, Xiansong
Jiang, Tian
Chen, Ping-Xing
Chen, Ruofan
author_facet Guo, Chu
Wu, Wei
Xu, Xiansong
Jiang, Tian
Chen, Ping-Xing
Chen, Ruofan
contents Based on the process tensor framework, we extend the time-evolving matrix product operator (TEMPO) method to solve bosonic quantum impurity problems (QIPs) with off-diagonal system-bath coupling. Our method is a most generic extension of TEMPO, which applies for any QIPs as long as the bath is noninteracting and the system is linearly coupled to the bath. It naturally contains all the current developments of TEMPO in more restricted settings. As an application, we study the real-time dynamics of a spin that is coupled to a sub-ohmic bath via the Jaynes-Cummings-type system-bath coupling, and compare it against that of the standard spin-boson model. Our results show that the commonly used secular approximation could easily fail in presence of a structural bath. Our method provides a unified framework to understand different variants of TEMPO and directly suggests a fermionic generalization which has not been explored so far, it could also be straightforwardly used as an impurity solver in the bosonic dynamical mean field theory.
format Preprint
id arxiv_https___arxiv_org_abs_2604_01556
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Time-evolving matrix product operators for off-diagonal system-bath coupling
Guo, Chu
Wu, Wei
Xu, Xiansong
Jiang, Tian
Chen, Ping-Xing
Chen, Ruofan
Mesoscale and Nanoscale Physics
Based on the process tensor framework, we extend the time-evolving matrix product operator (TEMPO) method to solve bosonic quantum impurity problems (QIPs) with off-diagonal system-bath coupling. Our method is a most generic extension of TEMPO, which applies for any QIPs as long as the bath is noninteracting and the system is linearly coupled to the bath. It naturally contains all the current developments of TEMPO in more restricted settings. As an application, we study the real-time dynamics of a spin that is coupled to a sub-ohmic bath via the Jaynes-Cummings-type system-bath coupling, and compare it against that of the standard spin-boson model. Our results show that the commonly used secular approximation could easily fail in presence of a structural bath. Our method provides a unified framework to understand different variants of TEMPO and directly suggests a fermionic generalization which has not been explored so far, it could also be straightforwardly used as an impurity solver in the bosonic dynamical mean field theory.
title Time-evolving matrix product operators for off-diagonal system-bath coupling
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2604.01556