Non-Abelian magnetic monopole in a Bose-Einstein condensate

TL;DR

This paper investigates the behavior of a non-Abelian magnetic monopole in a Bose-Einstein condensate, revealing how topological charge cancellation affects the monopole's gauge invariance and leading to a transition to vortex states.

Contribution

It demonstrates the cancellation of monopole charge by pseudospin topological charge in BECs and classifies stationary states based on laser wavelength effects.

Findings

Topological charge cancels monopole charge, resulting in zero gauge invariant charge.

Different stationary states are classified by their monopole effects.

A crossover to vortex ground states occurs as laser wavelength varies.

Abstract

Recently, an effective non-Abelian magnetic field with a topology of a monopole was shown to emerge from the adiabatic motion of multilevel atoms in spatially varying laser fields [J. Ruseckas et al., Phys. Rev. Lett. 95, 010404 (2005)]. We study this monopole in a Bose-Einstein condensate (BEC) of degenerate dressed states and find that the topological charge of the pseudospin cancels the monopole charge resulting in a vanishing gauge invariant charge. As a function of the laser wavelength, different stationary states are classified in terms of their effect to the monopole part of the magnetic field and a cross-over to vortex ground state is observed.