Tunable Hilbert space fragmentation and extended critical regime

Fuente: arXiv
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Auteurs principaux: Lisiecki, Mateusz, Bonča, Janez, Mierzejewski, Marcin, Herbrych, Jacek, Łydżba, Patrycja
Format: Preprint
Publié: 2025
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author Lisiecki, Mateusz
Bonča, Janez
Mierzejewski, Marcin
Herbrych, Jacek
Łydżba, Patrycja
author_facet Lisiecki, Mateusz
Bonča, Janez
Mierzejewski, Marcin
Herbrych, Jacek
Łydżba, Patrycja
contents Systems exhibiting the Hilbert-space fragmentation are nonergodic, and their Hamiltonians decompose into exponentially many blocks in the computational basis. In many cases, these blocks can be labeled by eigenvalues of statistically localized integrals of motion (SLIOM), which play a similar role in fragmented systems as local integrals of motion in integrable systems. While a nonzero perturbation eliminates all nontrivial conserved quantities from integrable models, we demonstrate for the $t$-$J_z$ chain that an appropriately chosen perturbation may gradually eliminate SLIOMs (one by one) by progressively merging the fragmented subspaces. This gradual recovery of ergodicity manifests as an extended critical regime characterized by multiple peaks of the fidelity susceptibility. Each peak signals a change in the number of SLIOMs and blocks, as well as an ultra-slow relaxation of local observables.
format Preprint
id arxiv_https___arxiv_org_abs_2505_09346
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Tunable Hilbert space fragmentation and extended critical regime
Lisiecki, Mateusz
Bonča, Janez
Mierzejewski, Marcin
Herbrych, Jacek
Łydżba, Patrycja
Strongly Correlated Electrons
Statistical Mechanics
Quantum Physics
Systems exhibiting the Hilbert-space fragmentation are nonergodic, and their Hamiltonians decompose into exponentially many blocks in the computational basis. In many cases, these blocks can be labeled by eigenvalues of statistically localized integrals of motion (SLIOM), which play a similar role in fragmented systems as local integrals of motion in integrable systems. While a nonzero perturbation eliminates all nontrivial conserved quantities from integrable models, we demonstrate for the $t$-$J_z$ chain that an appropriately chosen perturbation may gradually eliminate SLIOMs (one by one) by progressively merging the fragmented subspaces. This gradual recovery of ergodicity manifests as an extended critical regime characterized by multiple peaks of the fidelity susceptibility. Each peak signals a change in the number of SLIOMs and blocks, as well as an ultra-slow relaxation of local observables.
title Tunable Hilbert space fragmentation and extended critical regime
topic Strongly Correlated Electrons
Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2505.09346