Phase-slippage and self-trapping in a self-induced bosonic Josephson junction

TL;DR

This paper explores how a dipolar Bose-Einstein condensate in a toroidal trap can form a self-induced Josephson junction, exhibiting self-trapping and vortex-induced phase-slip dynamics that invert particle flux.

Contribution

It demonstrates the formation of a self-induced Josephson junction in a dipolar condensate and links self-trapping to vortex-induced phase slips, a novel dynamical behavior.

Findings

Self-trapping occurs with large initial population imbalance.

Vortices nucleate spontaneously in low-density regions.

Vortex dynamics cause phase slips and flux inversion.

Abstract

A dipolar condensate confined in a toroidal trap constitutes a self-induced Josepshon junction when the dipoles are oriented perpendicularly to the trap symmetry axis and the s-wave scattering length is small enough. The ring-shaped double-well potential coming from the anisotropic character of the mean-field dipolar interaction is robust enough to sustain self-trapping dynamics, which takes place when the initial population imbalance between the two wells is large. We show that in this system the self-trapping regime is directly related to a vortex-induced phase-slip dynamics. A vortex and antivortex are spontaneously nucleated in the low density regions, before a minimum of the population imbalance is reached, and then cross the toroidal section in opposite directions through the junctions.This vortex dynamics yields a phase slip between the two weakly linked condensates causing an inversion of the particle flux.