Nonlinear Self-Trapping of Matter Waves in Periodic Potentials

TL;DR

This paper presents the first experimental observation of nonlinear self-trapping of Bose-Einstein condensates in a periodic potential, demonstrating a transition from diffusion to localized trapping as nonlinearity increases.

Contribution

It provides the first experimental evidence of nonlinear self-trapping in a one-dimensional waveguide with a periodic potential, confirming theoretical predictions.

Findings

Observation of nonlinear self-trapping in Bose-Einstein condensates.

Transition from diffusive to self-trapped regime with increasing nonlinearity.

Quantitative agreement with discrete nonlinear equation solutions.

Abstract

We report the first experimental observation of nonlinear self-trapping of Bose-condensed 87Rb atoms in a one dimensional waveguide with a superimposed deep periodic potential . The trapping effect is confirmed directly by imaging the atomic spatial distribution. Increasing the nonlinearity we move the system from the diffusive regime, characterized by an expansion of the condensate, to the nonlinearity dominated self-trapping regime, where the initial expansion stops and the width remains finite. The data are in quantitative agreement with the solutions of the corresponding discrete nonlinear equation. Our results reveal that the effect of nonlinear self-trapping is of local nature, and is closely related to the macroscopic self-trapping phenomenon already predicted for double-well systems.