Mixed-isotope Bose-Einstein condensates in Rubidium

TL;DR

This paper investigates the ground state properties of mixed 87Rb and 85Rb Bose-Einstein condensates in a pancake-shaped trap, analyzing effects of interspecies interactions and symmetry breaking.

Contribution

It provides numerical analysis of symmetry-breaking thresholds and collapse instability in mixed isotope condensates with varying interspecies interactions.

Findings

Symmetry-breaking occurs with repulsive interactions.

Threshold for symmetry breaking is numerically determined.

Attractive interactions lead to collapse at high atom numbers.

Abstract

We consider the ground state properties of mixed Bose-Einstein condensates of 87Rb and 85Rb atoms in the isotropic pancake trap, for both signs of the interspecies scattering length. In the case of repulsive interspecies interaction, there are the axially-symmetric and symmetry-breaking ground states. The threshold for the symmetry breaking transition, which is related to appearance of a zero dipole-mode, is found numerically. For attractive interspecies interactions, the two condensates assume symmetric ground states for the numbers of atoms up to the collapse instability of the mixture.