Quantum Fragmentation in the Extended Quantum Breakdown Model

Abstract

We introduce a one-dimensional (1D) extended quantum breakdown model comprising a fermionic and a spin degree of freedom per site, and featuring a spatially asymmetric breakdown-type interaction between the fermions and spins. We analytically show that, in the absence of any magnetic field for the spins, the model exhibits Hilbert space fragmentation within each symmetry sector into exponentially many Krylov subspaces and hence displays non-thermal dynamics. Here, we demonstrate that the fragmentation naturally occurs in an entangled basis and thus provides an example of "quantum fragmentation." Besides establishing the nature of fragmentation analytically, we also study the long-time behavior of the entanglement entropy and its deviation from the expected Page value as a probe of ergodicity in the system. Upon introducing a non-trivial magnetic field for the spins, most of the Krylov subspaces merge and the model becomes chaotic. Finally, we study the effects of strong randomness on the system and observe behavior similar to that of many-body localized systems.

30 pages, 13 figures

References in corpus (13)

• Thermalization and its mechanism for generic isolated quantum systems
• Probing many-body dynamics on a 51-atom quantum simulator
• Many body localization and thermalization in quantum statistical mechanics
• Localization of interacting fermions at high temperature
• The distribution of the ratio of consecutive level spacings in random matrix ensembles
• Many body localization in Heisenberg XXZ magnet in a random field
• Emergent SU(2) dynamics and perfect quantum many-body scars
• Many-body localization dynamics from gauge invariance
• Dynamics in many-body localized quantum systems without disorder
• Scenario for delocalization in translation invariant systems
• Minimal model for Hilbert space fragmentation with local constraints
• Filling constraints on translation invariant dipole conserving systems
• From the Quantum Breakdown Model to the Lattice Gauge Theory

Cited by in corpus (5)

• Bosonic Quantum Breakdown Hubbard Model
• Two-dimensional quantum breakdown model with Krylov subspace many-body localization
• Entanglement cost hierarchies in quantum fragmented mixed states
• Dynamics in the presence of local symmetry-breaking impurities
• Exponential $U(1)$ Symmetry-Breaking Phase as a Disorder-Free Quantum Glass