Magnetic disorder and dynamical properties of a Bose-Einstein condensate in atomic waveguides

TL;DR

This paper explores how small wire shape fluctuations induce strong disorder potentials in atomic waveguides, causing condensate fragmentation and a transition from coherent to insulating phases, with results aligning with experiments.

Contribution

It provides a systematic analysis of disorder effects on Bose-Einstein condensates in waveguides, highlighting the disorder-induced fragmentation and phase crossover.

Findings

Small wire fluctuations cause strong disorder potentials.

Fragmentation of condensate near the wire surface.

Transition from coherent to Bose-glass phase in strong disorder.

Abstract

We systematically investigate the properties of the quenched disorder potential in an atomic waveguide, and study its effects to the dynamics of condensate in the strong disorder region. We show that even very small wire shape fluctuations can cause strong disorder potential along the wire direction, leading to the fragmentation phenomena as the condensate is close to the wire surface. The generic disorder potential is Gaussian correlated random potential with vanishing correlations in both short and long wavelength limits and with a strong correlation weight at a finite length scale, set by the atom-wire distance. When the condensate is fragmentized, we investigate the coherent and incoherent dynamics of the condensate, and demonstrate that it can undergo a crossover from a coherent condensate to an insulating Bose-glass phase in strong disorder (or low density) regime. Our numerical results obtained within the meanfield approximation are semi-quantitatively consistent with the experimental results.