Emergent fracton dynamics in a nonplanar dimer model

We study the late time relaxation dynamics of a pure U(1) lattice gauge theory in the form of a dimer model on a bilayer geometry. To this end, we first develop a proper notion of hydrodynamic transport in such a system by constructing a global conservation law that can be attributed to the presence of topological solitons. The correlation functions of local objects charged under this conservation law can then be used to study the universal properties of the dynamics at late times, applicable to both quantum and classical systems. Performing the time evolution via classically simulable automata circuits unveils a rich phenomenology of the system's nonequilibrium properties: For a large class of relevant initial states, local charges are effectively restricted to move along one-dimensional tubes within the quasi-two-dimensional system, displaying fracton-like mobility constraints. The timescale on which these tubes are stable diverges with increasing systems size, yielding a novel mechanism for nonergodic behavior in the thermodynamic limit. We further explore the role of geometry by studying the system in a quasi-one-dimensional limit, where the Hilbert space is strongly fragmented due to the emergence of an extensive number of conserved quantities. This provides an instance of a recently introduced concept of statistically localized integrals of motion, whose universal anomalous hydrodynamics we determine by a mapping to a problem of classical tracer diffusion. We conclude by discussing how our approach might generalize to study transport in other lattice gauge theories.

Automated summary

This study investigates the late time relaxation dynamics of a pure U(1) lattice gauge theory, revealing a rich phenomenology of the system's nonequilibrium properties such as fracton-like mobility constraints and a novel mechanism for nonergodic behavior in the thermodynamic limit. Additionally, the research explores the role of geometry and the emergence of statistically localized integrals of motion with anomalous hydrodynamics, providing insight into transport in other lattice gauge theories.