Symmetry breaking in interacting ring-shaped superflows of Bose-Einstein condensates

TL;DR

This paper explores how symmetry breaking influences the dynamics and final states of superflows in interacting Bose-Einstein condensates arranged in ring geometries, revealing controllable pathways to different angular momentum states.

Contribution

It introduces a mean-field model to analyze symmetry breaking effects in weakly interacting ring-shaped superflows, highlighting the role of fluxon formation and population imbalance.

Findings

Symmetry breaking affects vortex dynamics and superflow evolution.

Controllable symmetry breaking influences the final angular momentum states.

Population imbalance can drive the system to different final configurations.

Abstract

We demonstrate that the evolution of superflows in interacting persistent currents of ultracold gases is strongly affected by symmetry breaking of the quantum vortex dynamics. We study counter-propagating superflows in a system of two parallel rings in regimes of weak (a Josephson junction with tunneling through the barrier) and strong (rings merging across a reduced barrier) interactions. For the weakly interacting toroidal Bose-Einstein condensates, formation of rotational fluxons (Josephson vortices) is associated with spontaneous breaking of the rotational symmetry of the tunneling superflows. The influence of a controllable symmetry breaking on the final state of the merging counter-propagating superflows is investigated in the framework of a weakly dissipative mean-field model. It is demonstrated that the population imbalance between the merging flows and the breaking of the underlying rotational symmetry can drive the double-ring system to final states with different angular momenta.