Modulational instability criteria for two-component Bose-Einstein condensates

TL;DR

This paper derives explicit criteria for the modulational instability of two-component Bose-Einstein condensates, revealing extended instability regions and increased growth rates compared to uncoupled states, applicable to both symmetric and asymmetric configurations.

Contribution

The authors develop a general perturbative formalism without sign restrictions on parameters, providing new explicit instability criteria for coupled BECs.

Findings

Extended instability regions for coupled condensates.

Enhanced instability growth rates compared to uncoupled states.

Formalism applicable to asymmetric and symmetric condensate states.

Abstract

The stability of colliding Bose-Einstein condensates is investigated. A set of coupled Gross-Pitaevskii equations is thus considered, and analyzed via a perturbative approach. No assumption is made on the signs (or magnitudes) of the relevant parameters like the scattering lengths and the coupling coefficients. The formalism is therefore valid for asymmetric as well as symmetric coupled condensate wave states. A new set of explicit criteria is derived and analyzed. An extended instability region, in addition to an enhanced instability growth rate is predicted for unstable two component bosons, as compared to the individual (uncoupled) state.