Vortices in a Bose-Einstein condensate confined by an optical lattice

TL;DR

This paper studies vortex behavior in Bose-Einstein condensates within optical lattices, revealing how the lattice phase influences vortex stability, motion, and introduces a new vortex type linked to anti-phase solitons.

Contribution

It provides a detailed analysis of vortex dynamics under different optical lattice phases and introduces a novel vortex structure related to anti-phase solitons in strong lattice regimes.

Findings

Vortex stability depends on the OL phase relative to the magnetic trap.

In cosinusoidal OL, a stable vortex exists at the trap center.

A new vortex type involving anti-phase solitons is proposed.

Abstract

We investigate the dynamics of vortices in repulsive Bose-Einstein condensates in the presence of an optical lattice (OL) and a parabolic magnetic trap. The dynamics is sensitive to the phase of the OL potential relative to the magnetic trap, and depends less on the OL strength. For the cosinusoidal OL potential, a local minimum is generated at the trap's center, creating a stable equilibrium for the vortex, while in the case of the sinusoidal potential, the vortex is expelled from the center, demonstrating spiral motion. Cases where the vortex is created far from the trap's center are also studied, revealing slow outward-spiraling drift. Numerical results are explained in an analytical form by means of a variational approximation. Finally, motivated by a discrete model (which is tantamount to the case of the strong OL lattice), we present a novel type of vortex consisting of two pairs of anti-phase solitons.