Absence of thermalization after a local quench and strong violation of the eigenstate thermalization hypothesis

Fuente: arXiv
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Main Authors: Reimann, Peter, Eidecker-Dunkel, Christian
Format: Preprint
Published: 2026
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author Reimann, Peter
Eidecker-Dunkel, Christian
author_facet Reimann, Peter
Eidecker-Dunkel, Christian
contents Absence of thermalization after a global quantum quench is a well-established numerical observation in integrable many-body systems, and can be empirically related to a violation of the eigenstate thermalization hypothesis (ETH) in such models. Still, in many of those examples a weaker version of the conventional ETH (wETH) has been numerically reported or even rigorously proven. In this paper we show analytically and illustrate numerically that the absence of thermalization is already possible after a local quench. A closely related finding is a strong violation of the ETH, meaning that not even the wETH is fulfilled anymore. In our analytical explorations we focus on XX-spin-chain models with open boundary conditions, where the local quench is generated by initiating the system in thermal equilibrium and then suddenly switching on (or slightly changing) a single-spin impurity either at the end or in the center of the chain. Numerically we observe qualitatively similar phenomena also for more general XXZ-models in the case of an end-impurity, but not in the case of a central impurity.
format Preprint
id arxiv_https___arxiv_org_abs_2604_11392
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Absence of thermalization after a local quench and strong violation of the eigenstate thermalization hypothesis
Reimann, Peter
Eidecker-Dunkel, Christian
Statistical Mechanics
Quantum Physics
Absence of thermalization after a global quantum quench is a well-established numerical observation in integrable many-body systems, and can be empirically related to a violation of the eigenstate thermalization hypothesis (ETH) in such models. Still, in many of those examples a weaker version of the conventional ETH (wETH) has been numerically reported or even rigorously proven. In this paper we show analytically and illustrate numerically that the absence of thermalization is already possible after a local quench. A closely related finding is a strong violation of the ETH, meaning that not even the wETH is fulfilled anymore. In our analytical explorations we focus on XX-spin-chain models with open boundary conditions, where the local quench is generated by initiating the system in thermal equilibrium and then suddenly switching on (or slightly changing) a single-spin impurity either at the end or in the center of the chain. Numerically we observe qualitatively similar phenomena also for more general XXZ-models in the case of an end-impurity, but not in the case of a central impurity.
title Absence of thermalization after a local quench and strong violation of the eigenstate thermalization hypothesis
topic Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2604.11392