Interaction-enhanced many body localization in a generalized Aubry-Andre model

TL;DR

This paper investigates how interactions unexpectedly promote many-body localization in a generalized Aubry-Andre model, revealing a counter-intuitive phenomenon supported by theoretical analysis and numerical simulations.

Contribution

It demonstrates that the highest-energy band in the GPD model is inherently unstable, leading to interaction-enhanced MBL, and develops a mean-field theory validated by numerical methods.

Findings

Interaction enhances MBL in the GPD model.

High-energy band instability causes the counter-intuitive MBL.

Mean-field theory aligns with numerical results.

Abstract

We study the many-body localization (MBL) transition in a generalized Aubry-Andre model (also known as the GPD model) introduced in Phys. Rev. Lett. 114, 146601 (2015). In contrast to MBL in other disordered or quasiperiodic models, the interaction seems to unexpectedly enhance MBL in the GPD model in some parameter ranges. To understand this counter-intuitive result, we demonstrate that the highest-energy single-particle band in the GPD model is unstable against even infinitesimal disorder, which leads to this surprising MBL phenomenon in the interacting model. We develop a mean-field theory description to understand the coupling between extended and localized states, which we validate using extensive exact diagonalization and DMRG-X numerical results.