Many-body localization in one dimensional optical lattice with speckle disorder

TL;DR

This study investigates the many-body localization transition in a one-dimensional Heisenberg spin chain with speckle disorder, revealing that its universality class matches that of uncorrelated random disorder and highlighting the role of disorder correlations.

Contribution

The paper demonstrates that many-body localization in speckle disorder shares the same universality class as uncorrelated disorder and explores the effects of disorder correlations on the transition.

Findings

Localization transition matches uncorrelated disorder universality class

Distributions of local imbalance reveal ergodic grains in localized phase

Speckle disorder allows studying correlation effects on localization

Abstract

The many-body localization transition for Heisenberg spin chain with a speckle disorder is studied. Such a model is equivalent to a system of spinless fermions in an optical lattice with an additional speckle field. Our numerical results show that the many-body localization transition in speckle disorder falls within the same universality class as the transition in an uncorrelated random disorder, in contrast to the quasiperiodic potential typically studied in experiments. This hints at possibilities of experimental studies of the role of rare Griffiths regions and of the interplay of ergodic and localized grains at the many-body localization transition. Moreover, the speckle potential allows one to study the role of correlations in disorder on the transition. We study both spectral and dynamical properties of the system focusing on observables that are sensitive to the disorder type and its correlations. In particular, distributions of local imbalance at long times provide an experimentally available tool that reveals the presence of small ergodic grains even deep in the many-body localized phase in a correlated speckle disorder.