Phase-slips and vortex dynamics in Josephson oscillations between Bose-Einstein condensates

TL;DR

This paper investigates how vortex rings influence Josephson oscillations and phase slips in a Bose-Einstein condensate within a double-well trap, linking vortex dynamics to self-trapping phenomena.

Contribution

It reveals the role of vortex rings in phase slips and self-trapping in BEC Josephson dynamics, extending previous theories of vortex-induced phase slippage.

Findings

Vortex rings cause phase slips leading to self-trapping.

Large amplitude oscillations are linked to vortex ring dynamics.

Vortex rings are created and annihilated within the weak-link region.

Abstract

We study the relation between Josephson dynamics and topological excitations in a dilute Bose-Einstein condensate confined in a double-well trap. We show that the phase slips responsible for the self-trapping regime are created by vortex rings entering and annihilating inside the weak-link region or created at the center of the barrier and expanding outside the system. Large amplitude oscillations just before the onset of self-trapping are also strictly connected with the dynamics of vortex rings at the edges of the inter-well barrier. Our results extend and analyze the dynamics of the vortex-induced phase slippages suggested a few decades ago in relation to the "ac" Josephson effect of superconducting and superfluid helium systems.