Interface Tension of Bose-Einstein Condensates

TL;DR

This paper develops a method to calculate the interface tension in binary Bose-Einstein condensates, enabling comparison with experimental data and including finite-temperature effects.

Contribution

It introduces a simple approach combining Thomas-Fermi approximation with interface excess terms and Laplace equation, applicable across broad interaction regimes.

Findings

The method accurately reproduces experimental interface tension data.

Finite-temperature corrections are generally small outside weak segregation regimes.

Expressions for interface excesses are valid over a wide range of interaction parameters.

Abstract

Motivated by recent observations of phase-segregated binary Bose-Einstein condensates, we propose a method to calculate the excess energy due to the interface tension of a trapped configuration. By this method one should be able to numerically reproduce the experimental data by means of a simple Thomas-Fermi approximation, combined with interface excess terms and the Laplace equation. Using the Gross-Pitaevskii theory, we find expressions for the interface excesses which are accurate in a very broad range of the interspecies and intraspecies interaction parameters. We also present finite-temperature corrections to the interface tension which, aside from the regime of weak segregation, turn out to be small.