Vortex-lattice pinning in two-component Bose-Einstein condensates

TL;DR

This paper studies how optical lattices influence vortex arrangements in two-component Bose-Einstein condensates within the mean-field quantum-Hall regime, revealing phase diagrams and pinning behaviors.

Contribution

It provides the first detailed analysis of vortex-lattice structures and phase diagrams in two-component condensates under optical lattice pinning in the quantum-Hall regime.

Findings

Vortices are pinned at optical lattice maxima in strong pinning regimes.

Intermediate pinning leads to vortices aligning along lines of minimal potential.

The phase diagram depends on optical lattice strength and geometry.

Abstract

We investigate the vortex-lattice structure for single- and two-component Bose-Einstein condensates in the presence of an optical lattice, which acts as a pinning potential for the vortices. The problem is considered in the mean-field quantum-Hall regime, which is reached when the rotation frequency $\Omega$ of the condensate in a radially symmetric trap approaches the (radial) trapping frequency $\omega$ and the interactions between the atoms are weak. We determine the vortex-lattice phase diagram as a function of optical-lattice strength and geometry. In the limit of strong pinning the vortices are always pinned at the maxima of the optical-lattice potential, similar to the slow-rotation case. At intermediate pinning strength, however, due to the competition between interactions and pinning energy, a structure arises for the two-component case where the vortices are pinned on lines of minimal potential.