Hilbert space fragmentation and slow dynamics in particle-conserving quantum East models

Abstract

Quantum kinetically constrained models have recently attracted significant attention due to their anomalous dynamics and thermalization. In this work, we introduce a hitherto unexplored family of kinetically constrained models featuring a conserved particle number and strong inversion-symmetry breaking due to facilitated hopping. We demonstrate that these models provide a generic example of so-called quantum Hilbert space fragmentation, that is manifested in disconnected sectors in the Hilbert space that are not apparent in the computational basis. Quantum Hilbert space fragmentation leads to an exponential in system size number of eigenstates with exactly zero entanglement entropy across several bipartite cuts. These eigenstates can be probed dynamically using quenches from simple initial product states. In addition, we study the particle spreading under unitary dynamics launched from the domain wall state, and find faster than diffusive dynamics at high particle densities, that crosses over into logarithmically slow relaxation at smaller densities. Using a classically simulable cellular automaton, we reproduce the logarithmic dynamics observed in the quantum case. Our work suggests that particle conserving constrained models with inversion symmetry breaking realize so far unexplored universality classes of dynamics and invite their further theoretical and experimental studies.

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Cited by in corpus (32)

• Dynamical criticality of magnetization transfer in integrable spin chains
• Localised Dynamics in the Floquet Quantum East Model
• Exact quench dynamics of the Floquet quantum East model at the deterministic point
• Krylov Delocalization/Localization across Ergodicity Breaking
• Multipole groups and fracton phenomena on arbitrary crystalline lattices
• Glassy word problems: ultraslow relaxation, Hilbert space jamming, and computational complexity
• Emergent symmetries in prethermal phases of periodically driven quantum systems
• Freezing transition in particle-conserving East model
• Subspace restricted thermalization in a correlated-hopping model with strong Hilbert space fragmentation characterized by irreducible strings
• Anomalous transport in the kinetically constrained quantum East-West model
• Signatures of fragmentation for periodically driven fermions
• Local integrals of motion in dipole-conserving models with Hilbert space fragmentation
• Many-body critical non-Hermitian skin effect
• Disorder-Free Localization as a Purely Classical Effect
• Scar-induced imbalance in staggered Rydberg ladders
• Fragmentation, Zero Modes, and Collective Bound States in Constrained Models
• State-dependent mobility edge in kinetically constrained models
• Geometric constructions of generalized dual-unitary circuits from biunitarity
• Hilbert space fragmentation from lattice geometry
• Chirally-protected state manipulation by tuning one-dimensional statistics
• Probing Hilbert space fragmentation using controlled dephasing
• Graph theory and tunable slow dynamics in quantum East Hamiltonians
• Universal Freezing Transitions of Dipole-Conserving Chains
• Entanglement cost hierarchies in quantum fragmented mixed states
• Diagnostics of Hilbert space fragmentation, freezing transition, and its effects in the family of quantum East models involving varying range of constraints
• Dynamics in the presence of local symmetry-breaking impurities
• Vanishing correlations in stochastic and bistochastic controlled circuits
• Transport in a System with a Tower of Quantum Many-Body Scars
• Tunable Hilbert space fragmentation and extended critical regime
• Dissipative quantum North-East-Center model: steady-state phase diagram, universality and nonergodic dynamics
• Additional quantum many-body scars of the spin-$1$ $XY$ model with Fock-space cages and commutant algebras
• Obstruction to Ergodicity from Locality and $U(1)$ Higher Symmetries on the Lattice