Dynamical Instabilities in a two-component Bose condensate in a 1d optical lattice

TL;DR

This paper analyzes the stability of two-component Bose-Einstein condensates in a 1D optical lattice, revealing conditions for phase separation and how deep lattices can suppress this instability, enabling better control of mixed atomic species.

Contribution

It provides a detailed stability analysis of two-component BECs in optical lattices and demonstrates how lattice depth influences phase separation instabilities.

Findings

Rubidium-87 mixture shows similar stability to single-component condensates.

Sodium-Rubidium mixture exhibits phase separation instability at small wave vectors.

Deep optical lattices can suppress phase separation, facilitating contact and transport of different atomic species.

Abstract

In this paper we carry out a stability analysis of the Bloch states of a two-component Bose-Einstein condensate confined to a 1d optical lattice. We consider two concrete systems: a mixture of two hyperfine states of Rubidium-87 and a mixture of Sodium-23 and Rubidium-87. The former is seen to exhibit similar phenomena to a single component condensate while the latter also suffers an instability to phase separation at small Bloch wave vectors. It is shown that sufficiently deep optical lattices can remove this latter instability, potentially allowing imiscible cold atoms species to be held in intimate contact and transported within an experimental system.