Collective modes in multicomponent condensates with anisotropy

TL;DR

This paper investigates how anisotropy in the confining potential affects the low-energy excitations of two-component Bose-Einstein condensates, revealing modifications in dispersion relations and interface structures.

Contribution

It introduces a detailed theoretical analysis of anisotropy effects on TBECs using HFB theory, focusing on interface geometries and excitation spectra.

Findings

Anisotropy alters the energy and structure of quasiparticle excitation branches.

Dispersion relations for shell-structured interfaces are modified by anisotropy.

The study provides specific examples with Rb and Cs isotopes in different interface configurations.

Abstract

We report the effects of anisotropy in the confining potential on two component Bose-Einstein condensates (TBECs) through the properties of the low energy quasiparticle excitations. Starting from generalized Gross Pitaevskii equation, we obtain the Bogoliubov de-Gennes (BdG) equation for TBECs using the Hartree-Fock-Bogoliubov (HFB) theory. Based on this theory, we present the influence of radial anisotropy on TBECs in the immiscible or the phase-separated domain. In particular, the TBECs of $^{85}$Rb~-$^{87}$Rb and $^{133}$Cs~-$^{87}$Rb TBECs are chosen as specific examples of the two possible interface geometries, shell-structured and side by side, in the immiscible domain. We also show that the dispersion relation for the TBEC shell-structured interface has two branches, and anisotropy modifies the energy scale and structure of the two branches.