Existence, Stability and Dynamics of Monopole and Alice Ring Solutions in Anti-Ferromagnetic Spinor Condensates

TL;DR

This paper investigates the existence, stability, and dynamics of monopole and Alice ring topological defects in anti-ferromagnetic spinor condensates, revealing bifurcations, stability regimes, and dynamical behaviors through numerical methods.

Contribution

It identifies two bifurcating Alice ring solutions and analyzes their stability, providing new insights into topological defect dynamics in spinor condensates.

Findings

Monopole solutions are always dynamically unstable.

Larger Alice rings can be stable near bifurcation points.

Instability rates of smaller Alice rings can be reduced by adjusting trapping strengths.

Abstract

In this work we study the existence, stability, and dynamics of select topological point and line defects in anti-ferromagnetic, polar phase, $F=1$ $^{23}$Na spinor condensates. Specifically, we leverage fixed-point and numerical continuation techniques in three spatial dimensions to identify solution families of monopole and Alice rings as the chemical potential (number of atoms) and trapping strengths are varied within intervals of realizable experimental parameters. We are able to follow the monopole from the linear limit of small atom number all the way to the Thomas-Fermi regime of large atom number. Additionally, and importantly, our studies reveal the existence of {\em two} Alice ring solution branches, corresponding to, relatively, smaller and larger ring radii, that bifurcate from each other in a saddle-center bifurcation as the chemical potential is varied. We find that the monopole solution is always dynamically unstable in the regimes considered. In contrast, we find that the larger Alice ring is indeed stable close to the bifurcation point until it destabilizes from an oscillatory instability bubble for a larger value of the chemical potential. We also report on the possibility of dramatically reducing, yet not completely eliminating, the instability rates for the smaller Alice ring by varying the trapping strengths. The dynamical evolution of the different unstable waveforms is also probed via direct numerical simulations.