Obstruction to Ergodicity from Locality and $U(1)$ Higher Symmetries on the Lattice

Fuente: arXiv
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Main Authors: Sohal, Ramanjit, Verresen, Ruben
Format: Preprint
Published: 2025
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author Sohal, Ramanjit
Verresen, Ruben
author_facet Sohal, Ramanjit
Verresen, Ruben
contents We argue that the presence of \emph{any} exact $U(1)$ higher-form symmetry, under mild assumptions, presents a fundamental obstruction to ergodicity under unitary dynamics in lattice systems with local interactions and finite on-site Hilbert space dimension. Focusing on the two-dimensional case, we show that such systems necessarily exhibit Hilbert space fragmentation and explicitly construct Krylov sectors whose number scales exponentially with system size. While these sectors cannot be distinguished by symmetry quantum numbers, we identify the emergent integrals of motion which characterize them. Our symmetry-based approach is insensitive to details of the Hamiltonian and the lattice, providing a systematic explanation for ergodicity-breaking in a range of systems, including quantum link models.
format Preprint
id arxiv_https___arxiv_org_abs_2511_21815
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Obstruction to Ergodicity from Locality and $U(1)$ Higher Symmetries on the Lattice
Sohal, Ramanjit
Verresen, Ruben
Strongly Correlated Electrons
Statistical Mechanics
Quantum Physics
We argue that the presence of \emph{any} exact $U(1)$ higher-form symmetry, under mild assumptions, presents a fundamental obstruction to ergodicity under unitary dynamics in lattice systems with local interactions and finite on-site Hilbert space dimension. Focusing on the two-dimensional case, we show that such systems necessarily exhibit Hilbert space fragmentation and explicitly construct Krylov sectors whose number scales exponentially with system size. While these sectors cannot be distinguished by symmetry quantum numbers, we identify the emergent integrals of motion which characterize them. Our symmetry-based approach is insensitive to details of the Hamiltonian and the lattice, providing a systematic explanation for ergodicity-breaking in a range of systems, including quantum link models.
title Obstruction to Ergodicity from Locality and $U(1)$ Higher Symmetries on the Lattice
topic Strongly Correlated Electrons
Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2511.21815