Binary Bose-Einstein Condensate Mixtures in Weakly and Strongly Segregated Phases

TL;DR

This study explores the phase behavior of binary Bose-Einstein condensates under varying interaction strengths, identifying weakly and strongly segregated phases with distinct density and symmetry properties, and relates findings to experimental observations.

Contribution

It provides a mean-field analysis distinguishing weakly and strongly segregated phases and discusses the critical atom number for phase segregation, connecting theory with experiments.

Findings

Weakly segregated phase characterized by penetration depth.

Strongly segregated phase characterized by healing length.

Experimental data suggests observation of the weakly segregated phase.

Abstract

We perform a mean-field study of the binary Bose-Einstein condensate mixtures as a function of the mutual repulsive interaction strength. In the phase segregated regime, we find that there are two distinct phases: the weakly segregated phase characterized by a `penetration depth' and the strongly segregated phase characterized by a healing length. In the weakly segregated phase the symmetry of the shape of each condensate will not take that of the trap because of the finite surface tension, but its total density profile still does. In the strongly segregated phase even the total density profile takes a different symmetry from that of the trap because of the mutual exclusion of the condensates. The lower critical condensate-atom number to observe the complete phase segregation is discussed. A comparison to recent experimental data suggests that the weakly segregated phase has been observed.