Thermalization of exact quantum many-body scars in spin-1 XY chain under perturbation

Fuente: arXiv
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Main Author: Halder, Himadri
Format: Preprint
Published: 2025
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author Halder, Himadri
author_facet Halder, Himadri
contents Quantum many-body scars are special eigenstates that violate the eigenstate thermalization hypothesis while residing at finite energy density along with thermalizing eigenstates. The spin-1 XY model is known to host a family of such exceptional states originating from long-lived quasiparticle excitations that exhibit anomalously low entanglement entropy and long-time periodic revivals, resulting in weak ergodicity breaking. We study the stability of these scarred states against typical U(1) symmetry preserving perturbation in the XY chain. While perturbation theory can describe the deformed scar states at small system sizes, finite-size scaling of the perturbation matrix elements indicate that the scars ultimately thermalize in larger chains. Nonetheless, we demonstrate that the long-range order associated with the scars decays under the perturbation, and we estimate the relaxation timescale of oscillatory dynamics in certain local observables to be of order $λ^{-2}$, where $λ$ is the perturbation strength.
format Preprint
id arxiv_https___arxiv_org_abs_2511_17476
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Thermalization of exact quantum many-body scars in spin-1 XY chain under perturbation
Halder, Himadri
Strongly Correlated Electrons
Statistical Mechanics
Quantum Physics
Quantum many-body scars are special eigenstates that violate the eigenstate thermalization hypothesis while residing at finite energy density along with thermalizing eigenstates. The spin-1 XY model is known to host a family of such exceptional states originating from long-lived quasiparticle excitations that exhibit anomalously low entanglement entropy and long-time periodic revivals, resulting in weak ergodicity breaking. We study the stability of these scarred states against typical U(1) symmetry preserving perturbation in the XY chain. While perturbation theory can describe the deformed scar states at small system sizes, finite-size scaling of the perturbation matrix elements indicate that the scars ultimately thermalize in larger chains. Nonetheless, we demonstrate that the long-range order associated with the scars decays under the perturbation, and we estimate the relaxation timescale of oscillatory dynamics in certain local observables to be of order $λ^{-2}$, where $λ$ is the perturbation strength.
title Thermalization of exact quantum many-body scars in spin-1 XY chain under perturbation
topic Strongly Correlated Electrons
Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2511.17476