Many body localization and quantum non-ergodicity in a model with a single-particle mobility edge

TL;DR

This paper explores how a single-particle mobility edge influences many-body localization and ergodicity in an interacting 1D model, revealing a non-ergodic phase with volume law entanglement and proposing experimental tests.

Contribution

It demonstrates the emergence of a many-body mobility edge from a single-particle mobility edge in an interacting system and uncovers an extended non-ergodic phase.

Findings

Existence of a many-body mobility edge in the interacting model.

Identification of an extended non-ergodic phase with volume law EE.

Presence of an infinite temperature many-body localization transition.

Abstract

We investigate many body localization in the presence of a single particle mobility edge. By considering an interacting deterministic model with an incommensurate potential in one dimension we find that the single particle mobility edge in the noninteracting system leads to a many body mobility edge in the corresponding interacting system for certain parameter regimes. Using exact diagonalization, we probe the mobility edge via energy resolved entanglement entropy (EE) and study the energy resolved applicability (or failure) of the eigenstate thermalization hypothesis (ETH). Our numerical results indicate that the transition separating area and volume law scaling of the EE does not coincide with the non-thermal to thermal transition. Consequently, there exists an extended non-ergodic phase for an intermediate energy window where the many body eigenstates violate the ETH while manifesting volume law EE scaling. We also establish that the model possesses an infinite temperature many body localization transition despite the existence of a single particle mobility edge. We propose a practical scheme to test our predictions in atomic optical lattice experiments which can directly probe the effects of the mobility edge.