Observation of interaction-induced mobility edge in a disordered atomic wire

TL;DR

This paper experimentally demonstrates an interaction-induced mobility edge in a disordered atomic wire using a nonlinear Aubry-André model, revealing tunable localization transitions influenced by atomic interactions.

Contribution

It provides the first experimental evidence of a mobility edge induced by interactions in a nonlinear AA model, expanding understanding of quantum localization.

Findings

Mobility edge observed in a disordered atomic wire.

Mobility edge location is tunable by interactions.

Constructed a phase diagram showing extended-to-localized transitions.

Abstract

Mobility edge, a critical energy separating localized and extended excitations, is a key concept for understanding quantum localization. Aubry-Andr\'{e} (AA) model, a paradigm for exploring quantum localization, does not naturally allow mobility edges due to self-duality. Using the momentum-state lattice of quantum gas of Cs atoms to synthesize a nonlinear AA model, we provide experimental evidence for mobility edge induced by interactions. By identifying the extended-to-localized transition of different energy eigenstates, we construct a mobility-edge phase diagram. The location of mobility edge in the low- or high-energy region is tunable via repulsive or attractive interactions. Our observation is in good agreement with the theory, and supports an interpretation of such interaction-induced mobility edge via a generalized AA model. Our work also offers new possibilities to engineer quantum transport and phase transitions in disordered systems.