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

In Ref. [1], we study the many-body localization (MBL) transition in a generalized Aubry-Andre model (also known as the GPD model) introduced in Ref. [2]. In contrast to MBL in other disordered or quasiperiodic models, interaction seems to unexpectedly enhance MBL in the GPD model in some parameter range. 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.