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arXiv · 2605.24510

Strong Eigenstate Thermalization from Mean-Ergodic Non-chaotic Dynamics

Avadhut V. Purohit·Harshit Sharma·Udaysinh T. Bhosale
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Abstract

We report an example of a many-body system, derived from the double kicked top (DKT), with non-chaotic yet mean-ergodic dynamics that displays \textit{strong} eigenstate thermalization hypothesis (ETH) in the quantum regime. The analysis addresses a key open question: whether \textit{strong} ETH is a quantum analog of ergodicity (or mean-ergodicity). Despite non-chaotic dynamics, the fluctuations of the diagonal matrix elements of an observable scale as $D^{-1/2}$, where $D$ denotes the Hilbert space dimension. Furthermore, the off-diagonal matrix elements show parameter-independent distribution, together with a smooth function $f_O(\bar{E}, \omega)$ that becomes nearly uniform in the large-$k_\theta$ domain. Our findings show that even mean-ergodic and non-chaotic systems can exhibit \textit{strong} ETH.

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BibTeXRIS

Avadhut V. Purohit, Harshit Sharma, Udaysinh T. Bhosale. 2026-05-23. Strong Eigenstate Thermalization from Mean-Ergodic Non-chaotic Dynamics. https://arxiv.org/abs/2605.24510

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