Self-trapping in an array of coupled 1D Bose gases

TL;DR

This paper investigates the self-trapping phenomenon in arrays of coupled 1D Bose gases, revealing quantum correlation effects that suppress tunneling beyond mean-field predictions in ultracold atom experiments.

Contribution

It introduces a new type of self-trapping driven by quantum correlations, improving understanding of tunneling suppression in coupled Bose gases.

Findings

Transverse expansion delayed by atom interactions

Mean-field model shows localized self-trapping barrier

Quantum correlations further suppress tunneling

Abstract

We study the transverse expansion of arrays of ultracold $^{87}$Rb atoms weakly confined in tubes created by a 2D optical lattice, and observe that transverse expansion is delayed because of mutual atom interactions. A mean-field model of a coupled array shows that atoms become localized within a roughly square fort-like self-trapping barrier with time-evolving edges. But the observed dynamics is poorly described by the mean-field model. Theoretical introduction of random phase fluctuations among tubes improves the agreement with experiment, but does not correctly predict the density at which the atoms start to expand with larger lattice depths. Our results suggest a new type of self-trapping, where quantum correlations suppress tunneling even when there are no density gradients.