Collision dynamics and reactions of fractional vortex molecules in coherently coupled Bose-Einstein condensates

TL;DR

This paper investigates the collision dynamics of fractional vortex molecules in coherently coupled Bose-Einstein condensates, revealing reaction-like behaviors and selection rules similar to particle physics.

Contribution

It introduces a novel analogy between vortex molecule collisions in BECs and hadron reactions in QCD, including numerical simulations and reaction classification.

Findings

Vortex molecules swap partners during collisions.

Collision outcomes follow a selection rule similar to QCD.

Reactions can be summarized with Feynman diagrams.

Abstract

Coherently coupled two-component Bose-Einstein condensates (BEC) exhibit vortex confinement resembling quark confinement in Quantum Chromo Dynamics (QCD). Fractionally quantized vortices winding only in one of two components are attached by solitons, and they cannot stably exist alone. Possible stable states are "hadrons" either of mesonic type, i.e., molecules made of a vortex and anti-vortex in the same component connected by a soliton, or of baryonic type, i.e., molecules made of two vortices winding in two different components connected by a soliton. Mesonic molecules move straight with a constant velocity while baryonic molecules rotate. We numerically simulate collision dynamics of mesonic and baryonic molecules and find that the molecules swap a partner in collisions in general like chemical and nuclear reactions, summarize all collisions as vortex reactions, and describe those by Feynman diagrams. We find a selection rule for final states after collisions of vortex molecules, analogous to that for collisions of hadrons in QCD.