Guiding-center dynamics of vortex dipoles in Bose-Einstein condensates

TL;DR

This paper investigates the dynamics of vortex dipoles in Bose-Einstein condensates, revealing stable quasi-periodic epicyclic orbits through experimental observations and a vortex-particle model.

Contribution

It introduces a vortex-particle model that accurately predicts vortex dipole trajectories and uncovers their stable, quasi-periodic behavior in superfluid systems.

Findings

Vortex dipoles exhibit stable epicyclic orbits.

The vortex-particle model matches experimental trajectories.

Diverse vortex trajectories share similar quasi-periodic behavior.

Abstract

A quantized vortex dipole is the simplest vortex molecule, comprising two counter-circulating vortex lines in a superfluid. Although vortex dipoles are endemic in two-dimensional superfluids, the precise details of their dynamics have remained largely unexplored. We present here several striking observations of vortex dipoles in dilute-gas Bose-Einstein condensates, and develop a vortex-particle model that generates vortex line trajectories that are in good agreement with the experimental data. Interestingly, these diverse trajectories exhibit essentially identical quasi-periodic behavior, in which the vortex lines undergo stable epicyclic orbits.