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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…

Statistical Mechanics · Physics 2025-05-27 Shoki Sugimoto , Ryusuke Hamazaki , Masahito Ueda

The eigenstate thermalization hypothesis as well as the quantum ergodic theorem are studied in the light of quantum Fisher information. We show how global bounds on quantum Fisher information set the ETH and ergodicity conditions.…

High Energy Physics - Theory · Physics 2019-12-19 Cesar Gomez

A class of autonomous quantum heat baths satisfying the eigenstate thermalization hypothesis (ETH) criteria is proposed. We show that such systems are expected to cause thermal relaxation of much smaller quantum systems coupled to one of…

Quantum Physics · Physics 2015-08-10 O. Fialko

The validity of the ergodic hypothesis in quantum systems can be rephrased in the form of the eigenstate thermalisation hypothesis (ETH), a set of statistical properties for the matrix elements of local observables in energy eigenstates,…

Statistical Mechanics · Physics 2024-10-16 Miha Srdinšek , Tomaž Prosen , Spyros Sotiriadis

Eigenstate thermalization hypothesis (ETH) is discussed. We point out that the common formulation of the ETH suffers from the mixing of random and deterministic variables. We suggest a modified formulation of the ETH which includes only…

Statistical Mechanics · Physics 2018-11-05 Oleg Inozemcev , Igor Volovich

Despite the unitary evolution of closed quantum systems, long-time expectation of local observables are well described by thermal ensembles, providing the foundation of quantum statistical mechanics. A promising route to understanding this…

Quantum Physics · Physics 2026-02-03 Yuke Zhang , Pengfei Zhang

This review gives a pedagogical introduction to the eigenstate thermalization hypothesis (ETH), its basis, and its implications to statistical mechanics and thermodynamics. In the first part, ETH is introduced as a natural extension of…

Statistical Mechanics · Physics 2016-08-02 Luca D'Alessio , Yariv Kafri , Anatoli Polkovnikov , Marcos Rigol

We consider a quantum system A U B made up of degrees of freedom that can be partitioned into spatially disjoint regions A and B. When the full system is in a pure state in which regions A and B are entangled, the quantum mechanics of…

Statistical Mechanics · Physics 2014-11-27 Vedika Khemani , Anushya Chandran , Hyungwon Kim , S. L. Sondhi

We use exact diagonalization to study the eigenstate thermalization hypothesis (ETH) in the quantum dimer model on the square and triangular lattices. Due to the nonergodicity of the local plaquette-flip dynamics, the Hilbert space, which…

Statistical Mechanics · Physics 2017-09-25 Zhihao Lan , Stephen Powell

The Eigenstate Thermalization Hypothesis (ETH) has played a major role in understanding thermodynamic phenomena in closed quantum systems. However, its connection to the timescale of thermalization for open system dynamics has remained…

Quantum Physics · Physics 2023-03-30 Chi-Fang Chen , Fernando G. S. L. Brandão

We consider the set of all initial states within a microcanonical energy shell of an isolated many-body quantum system, which exhibit the same, arbitrary but fixed non-equilibrium expectation value for some given observable $A$. On…

Statistical Mechanics · Physics 2018-07-04 Peter Reimann

An isolated quantum many-body system in an initial pure state will come to thermal equilibrium if it satisfies the eigenstate thermalization hypothesis (ETH). We consider alternatives to ETH that have been proposed. We first show that von…

Statistical Mechanics · Physics 2012-03-15 Marcos Rigol , Mark Srednicki

We develop a class of matrix models which implement and formalize the `eigenstate thermalization hypothesis' (ETH) and point out that in general these models must contain non-Gaussian corrections, already in order to correctly capture…

High Energy Physics - Theory · Physics 2023-01-06 Daniel Louis Jafferis , David K. Kolchmeyer , Baur Mukhametzhanov , Julian Sonner

The eigenstate thermalization hypothesis (ETH) explains why chaotic quantum many-body systems thermalize internally if the Hamiltonian lacks symmetries. If the Hamiltonian conserves one quantity ("charge"), the ETH implies thermalization…

The Eigenstate Thermalization Hypothesis (ETH) provides a sufficient condition for thermalization of isolated quantum systems. While the standard ETH is formulated in the absence of degeneracy, physical systems often possess symmetries that…

High Energy Physics - Theory · Physics 2026-05-27 Soma Onoda , Osamu Fukushima , Ryusuke Hamazaki , Okuto Morikawa

Currently there are two main approaches to describe how quantum statistical physics emerges from an isolated quantum many-body system in a pure state: Canonical Typicality (CT) and Eigenstate Thermalization Hypothesis (ETH). These two…

Statistical Mechanics · Physics 2018-01-31 Anatoly Dymarsky , Hong Liu

We use the eigenstate thermalization hypothesis to derive a quantum master equation for a system weakly coupled to a chaotic finite-sized bath prepared in a pure state. We show that the emergence of Markovianity is controlled by the…

Quantum Physics · Physics 2025-09-03 Peter O'Donovan , Philipp Strasberg , Kavan Modi , John Goold , Mark T. Mitchison

According to the eigenstate thermalization hypothesis (ETH), the eigenstate-to-eigenstate fluctuations of expectation values of local observables should decrease with increasing system size. In approaching the thermodynamic limit - the…

Statistical Mechanics · Physics 2021-04-14 Goran Nakerst , Masudul Haque

The eigenstate thermalization hypothesis (ETH) and the theory of linear response (LRT) are celebrated cornerstones of our understanding of the physics of many-body quantum systems out of equilibrium. While the ETH provides a generic…

Statistical Mechanics · Physics 2019-05-29 Jonas Richter , Jochen Gemmer , Robin Steinigeweg

Under unitary time evolution, expectation values of physically reasonable observables often evolve towards the predictions of equilibrium statistical mechanics. The eigenstate thermalization hypothesis (ETH) states that this is also true…

Statistical Mechanics · Physics 2018-04-19 Fabio Anza , Christian Gogolin , Marcus Huber