Year: 2026
Type: article
Abstract: The t model represents the Hubbard model in the limit U →∞and is one of the basic models of stronglycorrelated electrons. On a one-dimensional chain, the model is integrable, and its charge dynamics is equivalentto that of free spinless fermions. However, within its dynamics the sequence of spins is frozen, implyingHilbert-space fragmentation and nontrivial spin dynamics. We focus primarily on perturbed versions of themodel in which the perturbations break integrability while preserving fragmentation. Considered examplesof such perturbations are spin-dependent hopping and additional spin interaction. We show that these modelsexhibit a variety of spin-transport regimes. In contrast to the integrable model, which displays either ballistictransport or dissipationless diffusion, the perturbed systems exhibit either normal diffusion or subdiffusion. Dueto Hilbert-space fragmentation, spin transport is mediated by charge transport in all cases considered. This leadsto a characteristic dependence on the magnetization, most notably resulting in subdiffusive spin transport in thegrand-canonical ensemble of the perturbed model. The underlying mechanism is distinct from the subdiffusionobserved in disordered systems or in models with dipole conservation.
Language: English
Topic: Quantum many-body systems
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223257604