Many-Body Localization in System with a Completely Delocalized Single-Particle Spectrum

TL;DR

This paper demonstrates that many-body localization can occur in a one-dimensional Fermi Hubbard model with completely delocalized single-particle states, challenging the notion that localization requires single-particle localization.

Contribution

It shows that strong disordered interactions can induce MBL even when the single-particle spectrum is fully delocalized, providing a new platform to study pure MBL phenomena.

Findings

MBL occurs in a model with no single-particle localization

Symmetries significantly affect charge transport

Proposes cold atom experiments for realization

Abstract

Many-body localization (MBL) in a one-dimensional Fermi Hubbard model with random on-site interactions is studied. While for this model all single-particle states are trivially delocalized, it is shown that for sufficiently strong disordered interactions the model is many-body localized. It is therefore argued that MBL does not necessary rely on localization of the single-particle spectrum. This model provides a convenient platform to study pure MBL phenomenology, since Anderson localization in this model does not exist. By examining various forms of the interaction term a dramatic effect of symmetries on charge transport is demonstrated. A possible realization in a cold atom experiments is proposed.