Confined p-band Bose-Einstein condensates

TL;DR

This paper investigates how confinement affects the properties of p-band Bose-Einstein condensates in a 2D optical lattice, revealing anisotropic densities and the disappearance of vortex order at the edges due to trapping.

Contribution

It provides a mean-field analysis of confined p-band BECs, highlighting anisotropic effects and the impact of trapping on vortex-antivortex order.

Findings

Atomic density becomes anisotropic under confinement.

Weak interactions and lattice amplitudes enhance anisotropic effects.

Vortex-antivortex order disappears at the edges of the condensate.

Abstract

We study bosonic atoms on the p-band of a two dimensional optical square lattice in the presence of a confining trapping potential. Using a mean-field approach, we show how the anisotropic tunneling for p-band particles affects the cloud of condensed atoms by characterizing the ground state density and the coherence properties of the atomic states both between sites and atomic flavors. In contrast to the usual results based on the local density approximation, the atomic density can become anisotropic. This anisotropic effect is especially pronounced in the limit of weak atom-atom interactions and of weak lattice amplitudes, i.e. when the properties of the ground state are mainly driven by the kinetic energies. We also investigate how the trap influences known properties of the non-trapped case. In particular, we focus on the behavior of the anti-ferromagnetic vortex-antivortex order, which for the confined system, is shown to disappear at the edges of the condensed cloud.