Exact Thermal Eigenstates of Nonintegrable Spin Chains at Infinite Temperature

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Hauptverfasser: Chiba, Yuuya, Yoneta, Yasushi
Format: Preprint
Veröffentlicht: 2024
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author Chiba, Yuuya
Yoneta, Yasushi
author_facet Chiba, Yuuya
Yoneta, Yasushi
contents The eigenstate thermalization hypothesis (ETH) plays a major role in explaining thermalization of isolated quantum many-body systems. However, there has been no proof of the ETH in realistic systems due to the difficulty in the theoretical treatment of thermal energy eigenstates of nonintegrable systems. Here, we write down analytically thermal eigenstates of nonintegrable spin chains. We consider a class of theoretically tractable volume-law states, which we call entangled antipodal pair (EAP) states. These states are thermal, in the most fundamental sense that they are indistinguishable from the Gibbs state with respect to all local observables, with infinite temperature. We then identify Hamiltonians having the EAP state as an eigenstate and rigorously show that some of these Hamiltonians are nonintegrable. Furthermore, a thermal pure state at an arbitrary temperature is obtained by the imaginary time evolution of an EAP state. Our results offer a potential avenue for providing a provable example of the ETH.
format Preprint
id arxiv_https___arxiv_org_abs_2403_12330
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Exact Thermal Eigenstates of Nonintegrable Spin Chains at Infinite Temperature
Chiba, Yuuya
Yoneta, Yasushi
Statistical Mechanics
Quantum Physics
The eigenstate thermalization hypothesis (ETH) plays a major role in explaining thermalization of isolated quantum many-body systems. However, there has been no proof of the ETH in realistic systems due to the difficulty in the theoretical treatment of thermal energy eigenstates of nonintegrable systems. Here, we write down analytically thermal eigenstates of nonintegrable spin chains. We consider a class of theoretically tractable volume-law states, which we call entangled antipodal pair (EAP) states. These states are thermal, in the most fundamental sense that they are indistinguishable from the Gibbs state with respect to all local observables, with infinite temperature. We then identify Hamiltonians having the EAP state as an eigenstate and rigorously show that some of these Hamiltonians are nonintegrable. Furthermore, a thermal pure state at an arbitrary temperature is obtained by the imaginary time evolution of an EAP state. Our results offer a potential avenue for providing a provable example of the ETH.
title Exact Thermal Eigenstates of Nonintegrable Spin Chains at Infinite Temperature
topic Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2403.12330