Critical Dynamics of the Anderson Transition on Small-World Graphs

TL;DR

This paper investigates the critical dynamics of the Anderson transition on Small-World graphs, revealing slow non-ergodic behavior at criticality and providing insights relevant to many-body localization and quantum simulation experiments.

Contribution

It constructs a unitary Anderson model on Small-World graphs and characterizes the dynamical properties across the transition, highlighting two distinct localization times and their scaling behaviors.

Findings

Logarithmically slow non-ergodic dynamics at criticality

Two localization times with diverging average and saturated typical times

Crossover from non-ergodic to ergodic diffusion in the delocalized regime

Abstract

The Anderson transition on random graphs draws interest through its resemblance to the many-body localization (MBL) transition with similarly debated properties. In this Letter, we construct a unitary Anderson model on Small-World graphs to characterize long time and large size wave-packet dynamics across the Anderson transition. We reveal the logarithmically slow non-ergodic dynamics in the critical regime, confirming recent random matrix predictions. Our data clearly indicate two localization times: an average localization time that diverges, while the typical one saturates. In the delocalized regime, the dynamics are initially non-ergodic but cross over to ergodic diffusion at long times and large distances. Finite-time scaling then allows us to characterize the critical dynamical properties: the logarithm of the average localization time diverges algebraically, while the ergodic time diverges exponentially. Our results could be used to clarify the dynamical properties of MBL and could guide future experiments with quantum simulators.