Bounds on eigenstate thermalization

Fuente: arXiv
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Autori principali: Sugimoto, Shoki, Hamazaki, Ryusuke, Ueda, Masahito
Natura: Preprint
Pubblicazione: 2023
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author Sugimoto, Shoki
Hamazaki, Ryusuke
Ueda, Masahito
author_facet Sugimoto, Shoki
Hamazaki, Ryusuke
Ueda, Masahito
contents The eigenstate thermalization hypothesis (ETH), which asserts that every eigenstate of a many-body quantum system is indistinguishable from a thermal ensemble, plays a pivotal role in understanding thermalization of isolated quantum systems. Yet, no evidence has been obtained as to whether the ETH holds for all few-body operators in a chaotic system; such few-body operators include key quantities in statistical mechanics, such as the total magnetization, the momentum distributions, and their low-order thermal and quantum fluctuations. Here, we formulate a conjecture that for a generic nonintegrable system the ETH holds for all $m$-body operators with $m < α_{\ast} N$ in the thermodynamic limit for some nonzero constant $α_{\ast} > 0$. We first prove this statement for systems with Haar-distributed energy eigenstates to analytically motivate our conjecture. We then verify the conjecture for generic spin, Bose, and Fermi systems with local and few-body interactions by large-scale numerical calculations. Our results imply that generic systems satisfy the ETH for all few-body operators, including their thermal and quantum fluctuations.
format Preprint
id arxiv_https___arxiv_org_abs_2303_10069
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Bounds on eigenstate thermalization
Sugimoto, Shoki
Hamazaki, Ryusuke
Ueda, Masahito
Statistical Mechanics
Quantum Physics
The eigenstate thermalization hypothesis (ETH), which asserts that every eigenstate of a many-body quantum system is indistinguishable from a thermal ensemble, plays a pivotal role in understanding thermalization of isolated quantum systems. Yet, no evidence has been obtained as to whether the ETH holds for all few-body operators in a chaotic system; such few-body operators include key quantities in statistical mechanics, such as the total magnetization, the momentum distributions, and their low-order thermal and quantum fluctuations. Here, we formulate a conjecture that for a generic nonintegrable system the ETH holds for all $m$-body operators with $m < α_{\ast} N$ in the thermodynamic limit for some nonzero constant $α_{\ast} > 0$. We first prove this statement for systems with Haar-distributed energy eigenstates to analytically motivate our conjecture. We then verify the conjecture for generic spin, Bose, and Fermi systems with local and few-body interactions by large-scale numerical calculations. Our results imply that generic systems satisfy the ETH for all few-body operators, including their thermal and quantum fluctuations.
title Bounds on eigenstate thermalization
topic Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2303.10069