Nonergodicity from Hilbert-Subspace Cloning
Abstract
We identify a class of nonintegrable quantum many-body systems composed of single Pauli strings that possess an extensive number of noncommuting local conserved quantities and exhibit partial ergodicity breaking due to exponentially degenerate energy spectra. We show that such systems exhibit a novel mechanism, Hilbert-subspace cloning, where the identical chaotic Hamiltonian acts on each of exponentially many disconnected Hilbert subspaces. Although the dynamics within each clone thermalizes, quantum coherence between clones remains protected and detectable by local observables. Consequently, the long-time behavior of local observables is described by a coherence-preserving partial Gibbs ensemble, where the hidden subsystem retains its initial quantum coherence.
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BibTeX
@misc{chiba2026nonergodicity,
title = {{Nonergodicity from Hilbert-Subspace Cloning}},
author = {Yuuya Chiba and Ryusuke Hamazaki},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.23105},
eprint = {2610.23105},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.23105},
}
RIS
TY - UNPB
TI - Nonergodicity from Hilbert-Subspace Cloning
AU - Yuuya Chiba
AU - Ryusuke Hamazaki
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.23105
UR - https://arxiv.org/abs/2610.23105
AB - We identify a class of nonintegrable quantum many-body systems composed of single Pauli strings that possess an extensive number of noncommuting local conserved quantities and exhibit partial ergodicity breaking due to exponentially degenerate energy spectra. We show that such systems exhibit a novel mechanism, Hilbert-subspace cloning, where the identical chaotic Hamiltonian acts on each of exponentially many disconnected Hilbert subspaces. Although the dynamics within each clone thermalizes, quantum coherence between clones remains protected and detectable by local observables. Consequently, the long-time behavior of local observables is described by a coherence-preserving partial Gibbs ensemble, where the hidden subsystem retains its initial quantum coherence.
ER -