Adiabatic gauge potential and integrability breaking with free fermions

Fuente: arXiv
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Main Authors: Pozsgay, Balázs, Sharipov, Rustem, Tiutiakina, Anastasiia, Vona, István
Format: Preprint
Published: 2024
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author Pozsgay, Balázs
Sharipov, Rustem
Tiutiakina, Anastasiia
Vona, István
author_facet Pozsgay, Balázs
Sharipov, Rustem
Tiutiakina, Anastasiia
Vona, István
contents We revisit the problem of integrability breaking in free fermionic quantum spin chains. We investigate the so-called adiabatic gauge potential (AGP), which was recently proposed as an accurate probe of quantum chaos. We also study the so-called weak integrability breaking, which occurs if the dynamical effects of the perturbation do not appear at leading order in the perturbing parameter. A recent statement in the literature claimed that integrability breaking should generally lead to an exponential growth of the AGP norm with respect to the volume. However, afterwards it was found that weak integrability breaking is a counter-example, leading to a cross-over between polynomial and exponential growth. Here we show that in free fermionic systems the AGP norm always grows polynomially, if the perturbation is local with respect to the fermions, even if the perturbation strongly breaks integrability. As a by-product of our computations we also find, that in free fermionic spin chains there are operators which weakly break integrability, but which are not associated with known long range deformations.
format Preprint
id arxiv_https___arxiv_org_abs_2402_12979
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Adiabatic gauge potential and integrability breaking with free fermions
Pozsgay, Balázs
Sharipov, Rustem
Tiutiakina, Anastasiia
Vona, István
Statistical Mechanics
We revisit the problem of integrability breaking in free fermionic quantum spin chains. We investigate the so-called adiabatic gauge potential (AGP), which was recently proposed as an accurate probe of quantum chaos. We also study the so-called weak integrability breaking, which occurs if the dynamical effects of the perturbation do not appear at leading order in the perturbing parameter. A recent statement in the literature claimed that integrability breaking should generally lead to an exponential growth of the AGP norm with respect to the volume. However, afterwards it was found that weak integrability breaking is a counter-example, leading to a cross-over between polynomial and exponential growth. Here we show that in free fermionic systems the AGP norm always grows polynomially, if the perturbation is local with respect to the fermions, even if the perturbation strongly breaks integrability. As a by-product of our computations we also find, that in free fermionic spin chains there are operators which weakly break integrability, but which are not associated with known long range deformations.
title Adiabatic gauge potential and integrability breaking with free fermions
topic Statistical Mechanics
url https://arxiv.org/abs/2402.12979