Collisional Dynamics of Half-Quantum Vortices in a Spinor Bose-Einstein Condensate

TL;DR

This paper experimentally investigates the interactions, collision dynamics, and relaxation processes of half-quantum vortices in a spinor Bose-Einstein condensate, revealing short-range vortex interactions and spin wave excitations.

Contribution

It provides the first experimental observation of HQV collision dynamics and their coupling with spin waves in a spinor BEC.

Findings

HQV collisions follow short-range interaction patterns.

Spin wave excitations are generated by HQV collisions.

HQV-magnon coupling is characterized in the experiment.

Abstract

We present an experimental study on the interaction and dynamics of half-quantum vortices (HQVs) in an antiferromagnetic spinor Bose-Einstein condensate. By exploiting the orbit motion of a vortex dipole in a trapped condensate, we perform a collision experiment of two HQV pairs, and observe that the scattering motions of the HQVs is consistent with the short-range vortex interaction that arises from nonsingular magnetized vortex cores. We also investigate the relaxation dynamics of turbulent condensates containing many HQVs, and demonstrate that spin wave excitations are generated by the collisional motions of the HQVs. The short-range vortex interaction and the HQV-magnon coupling represent two characteristics of the HQV dynamics in the spinor superfluid.