Disordered Bose-Einstein Condensates in Quasi One-Dimensional Magnetic Microtraps

TL;DR

This paper investigates how random magnetic potentials in microtraps cause fragmentation of Bose-Einstein condensates and explores the possibility of observing a superfluid to Bose glass phase transition.

Contribution

It provides a quantitative theory linking wire-induced magnetic disorder to condensate fragmentation and suggests nonlinear dynamics as a tool to understand strongly disordered condensates.

Findings

Disorder induces quasiperiodic potential fluctuations affecting condensate shape.

Fragmentation of BECs observed experimentally can be explained by wire-induced disorder.

Potential for detecting a superfluid to Bose glass transition in realistic conditions.

Abstract

We analyze effects of a random magnetic potential in a microfabricated waveguide for ultra-cold atoms. We find that the shape and position fluctuations of a current carrying wire induce strongly disordered potential that is quasiperiodic with a lengthscale set by the atom-wire separation. The theory is used to explain quantitatively the experimentally observed fragmentation of the quasi one-dimensional Bose-Einstein condensates. Furthermore, we show that nonlinear dynamics can be used to provide important insights into the nature of the strongly fragmented condensates. We argue that a quantum phase transition from the superfluid to the insulating Bose glass phase may be reached and detected under the realistic experimental conditions.