Coherence-induced deep thermalization transition in random permutation quantum dynamics

Fuente: arXiv
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Hauptverfasser: Liu, Chang, Ippoliti, Matteo, Ho, Wen Wei
Format: Preprint
Veröffentlicht: 2025
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author Liu, Chang
Ippoliti, Matteo
Ho, Wen Wei
author_facet Liu, Chang
Ippoliti, Matteo
Ho, Wen Wei
contents We report a phase transition in the projected ensemble - the collection of post-measurement wavefunctions of a local subsystem obtained by measuring its complement. The transition emerges in systems undergoing random permutation dynamics, a type of quantum time evolution wherein computational basis states are shuffled without creating superpositions. It separates a phase exhibiting deep thermalization, where the projected ensemble is distributed over Hilbert space in a maximally entropic fashion (Haar-random), from a phase where it is minimally entropic ("classical bit-string ensemble"). Crucially, this deep thermalization transition is invisible to the subsystem's density matrix, which always exhibits thermalization to infinite-temperature across the phase diagram. Through a combination of analytical arguments and numerical simulations, we show that the transition is tuned by the total amount of coherence injected by the input state and the measurement basis, and is exhibited robustly across different microscopic models. Our findings represent a novel form of ergodicity-breaking universality in quantum many-body dynamics, characterized not by a failure of regular thermalization, but rather by a failure of deep thermalization.
format Preprint
id arxiv_https___arxiv_org_abs_2510_18369
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Coherence-induced deep thermalization transition in random permutation quantum dynamics
Liu, Chang
Ippoliti, Matteo
Ho, Wen Wei
Quantum Physics
Statistical Mechanics
We report a phase transition in the projected ensemble - the collection of post-measurement wavefunctions of a local subsystem obtained by measuring its complement. The transition emerges in systems undergoing random permutation dynamics, a type of quantum time evolution wherein computational basis states are shuffled without creating superpositions. It separates a phase exhibiting deep thermalization, where the projected ensemble is distributed over Hilbert space in a maximally entropic fashion (Haar-random), from a phase where it is minimally entropic ("classical bit-string ensemble"). Crucially, this deep thermalization transition is invisible to the subsystem's density matrix, which always exhibits thermalization to infinite-temperature across the phase diagram. Through a combination of analytical arguments and numerical simulations, we show that the transition is tuned by the total amount of coherence injected by the input state and the measurement basis, and is exhibited robustly across different microscopic models. Our findings represent a novel form of ergodicity-breaking universality in quantum many-body dynamics, characterized not by a failure of regular thermalization, but rather by a failure of deep thermalization.
title Coherence-induced deep thermalization transition in random permutation quantum dynamics
topic Quantum Physics
Statistical Mechanics
url https://arxiv.org/abs/2510.18369