Discrete time crystals enabled by Floquet strong Hilbert space fragmentation

Fuente: arXiv
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Main Authors: Tang, Ling-Zhi, Li, Xiao, Wang, Z. D., Zhang, Dan-Wei
Format: Preprint
Published: 2025
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author Tang, Ling-Zhi
Li, Xiao
Wang, Z. D.
Zhang, Dan-Wei
author_facet Tang, Ling-Zhi
Li, Xiao
Wang, Z. D.
Zhang, Dan-Wei
contents Discrete time crystals (DTCs) are non-equilibrium phases of matter that break the discrete time-translation symmetry and is characterized by a robust subharmonic response in periodically driven quantum systems. Here, we explore the DTC in a disorder-free, periodically kicked XXZ spin chain, which is stabilized by the Floquet strong Hilbert space fragmentation. We numerically show the period-doubling response of the conventional DTC order, and uncover a multiple-period response with beating dynamics due to the coherent interplay of multiple $π$-pairs in the Floquet spectrum of small-size systems. The lifetime of the DTC order exhibits independence of the driving frequency and a power-law dependence on the ZZ interaction strength. It also grows exponentially with the system size, as a hallmark of the strong fragmentation inherent to the Floquet model. We analytically reveal the approximate conservation of the magnetization and domain-wall number in the Floquet operator for the emergent strong fragmentation, which is consistent with numerical results of the dimensionality ratio of symmetry subspaces. The rigidity and phase regime of the DTC order are identified through finite-size scaling of the Floquet-spectrum-averaged mutual information, as well as via dynamical probes. Our work establishes the Floquet Hilbert space fragmentation as a disorder-free mechanism for sustaining nontrivial temporal orders in out-of-equilibrium quantum many-body systems.
format Preprint
id arxiv_https___arxiv_org_abs_2512_14182
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Discrete time crystals enabled by Floquet strong Hilbert space fragmentation
Tang, Ling-Zhi
Li, Xiao
Wang, Z. D.
Zhang, Dan-Wei
Quantum Physics
Disordered Systems and Neural Networks
Quantum Gases
Discrete time crystals (DTCs) are non-equilibrium phases of matter that break the discrete time-translation symmetry and is characterized by a robust subharmonic response in periodically driven quantum systems. Here, we explore the DTC in a disorder-free, periodically kicked XXZ spin chain, which is stabilized by the Floquet strong Hilbert space fragmentation. We numerically show the period-doubling response of the conventional DTC order, and uncover a multiple-period response with beating dynamics due to the coherent interplay of multiple $π$-pairs in the Floquet spectrum of small-size systems. The lifetime of the DTC order exhibits independence of the driving frequency and a power-law dependence on the ZZ interaction strength. It also grows exponentially with the system size, as a hallmark of the strong fragmentation inherent to the Floquet model. We analytically reveal the approximate conservation of the magnetization and domain-wall number in the Floquet operator for the emergent strong fragmentation, which is consistent with numerical results of the dimensionality ratio of symmetry subspaces. The rigidity and phase regime of the DTC order are identified through finite-size scaling of the Floquet-spectrum-averaged mutual information, as well as via dynamical probes. Our work establishes the Floquet Hilbert space fragmentation as a disorder-free mechanism for sustaining nontrivial temporal orders in out-of-equilibrium quantum many-body systems.
title Discrete time crystals enabled by Floquet strong Hilbert space fragmentation
topic Quantum Physics
Disordered Systems and Neural Networks
Quantum Gases
url https://arxiv.org/abs/2512.14182