Non-equilibrium evolution of window overlaps in spin glasses

TL;DR

This study numerically examines the non-equilibrium evolution of window overlaps in 3D Ising spin glasses, revealing how local spin configurations depend on distant states and connecting dynamics to theoretical metastate concepts.

Contribution

It provides large-scale GPU simulations of spin glass dynamics, demonstrating scaling of window overlaps and the influence of global equilibration on local behavior.

Findings

Window overlaps scale with the ratio W/ξ(t)

Long-time dynamics show dependence on distant configurations

Global equilibration alters local overlap behavior

Abstract

We investigate numerically the time dependence of "window" overlaps in a three-dimensional Ising spin glass below its transition temperature after a rapid quench. Using an efficient GPU implementation, we are able to study large systems up to lateral length $L=128$ and up to long times of $t=10^8$ sweeps. We find that the data scales according to the ratio of the window size $W$ to the non-equilibrium coherence length $\xi(t)$. We also show a substantial change in behavior if the system is run for long enough that it globally equilibrates, i.e. $\xi(t) \approx L/2$, where $L$ is the lattice size. This indicates that the local behavior of a spin glass depends on the spin configurations (and presumably also the bonds) far away. We compare with similar simulations for the Ising ferromagnet. Based on these results, we speculate on a connection between the non-equilibrium dynamics discussed here and averages computed theoretically using the "metastate".