Non-Gaussian Spatial Correlations Dramatically Weaken Localization

TL;DR

This study reveals that non-Gaussian spatial correlations in disordered systems significantly weaken Anderson localization, with interactions reducing conductance without delocalizing wave functions.

Contribution

It demonstrates that non-Gaussian correlations, not just disorder strength, play a crucial role in localization phenomena in interacting disordered systems.

Findings

Quasiparticle wave functions remain localized despite interactions.

Interactions decrease the conductance scale g*, indicating stronger localization.

Non-Gaussian correlations in the screened potential weaken localization effects.

Abstract

We perform variational studies of the interaction-localization problem to describe the interaction-induced renormalizations of the effective (screened) random potential seen by quasiparticles. Here we present results of careful finite-size scaling studies for the conductance of disordered Hubbard chains at half-filling and zero temperature. While our results indicate that quasiparticle wave functions remain exponentially localized even in the presence of moderate to strong repulsive interactions, we show that interactions produce a strong decrease of the characteristic conductance scale g* signaling the crossover to strong localization. This effect, which cannot be captured by a simple renormalization of the disorder strength, instead reflects a peculiar non-Gaussian form of the spatial correlations of the screened disordered potential, a hitherto neglected mechanism to dramatically reduce the impact of Anderson localization (interference) effects.