Interaction-driven breakdown of dynamical localization in a kicked quantum gas

TL;DR

This paper experimentally investigates how many-body interactions affect dynamical localization in a kicked quantum gas, revealing a transition to many-body quantum chaos and the destruction of localization due to interactions.

Contribution

It demonstrates the first tunable many-body kicked quantum rotor using a Bose-Einstein condensate and explores how interactions induce a transition from localization to chaos.

Findings

Observation of a prethermal localized plateau

Interaction-induced anomalous diffusion with an exponent near 0.5

Interactions destroy reversibility in time reversal experiments

Abstract

Quantum interference can terminate energy growth in a continually kicked system, via a single-particle ergodicity-breaking mechanism known as dynamical localization. The effect of many-body interactions on dynamically localized states, while important to a fundamental understanding of quantum decoherence, has remained unexplored despite a quarter-century of experimental studies. We report the experimental realization of a tunably-interacting kicked quantum rotor ensemble using a Bose-Einstein condensate in a pulsed optical lattice. We observe signatures of a prethermal localized plateau, followed for interacting samples by interaction-induced anomalous diffusion with an exponent near one half. Echo-type time reversal experiments establish the role of interactions in destroying reversibility. These results quantitatively elucidate the dynamical transition to many-body quantum chaos, advance our understanding of quantum anomalous diffusion, and delimit some possibilities for protecting quantum information in interacting driven systems.