Modulational Instabity of Spin-Orbit Coupled Bose-Einstein Condensates in Discrete Media

TL;DR

This paper investigates how intra-site spin-orbit and Rabi couplings influence the modulational instability of plane-wave states in two-component discrete Bose-Einstein condensates, providing analytical conditions and numerical verification.

Contribution

It introduces analytical stability criteria for MI in spin-orbit coupled BECs in discrete media, highlighting the role of Rabi coupling and enabling experimental applications.

Findings

SO coupling induces MI at small wavenumbers.

Rabi coupling has a significant impact on stability.

Numerical results confirm linear stability analysis.

Abstract

We address the impact of intra-site spin-orbit (SO) coupling and associated inter-component Rabi coupling on the modulational instability (MI) of plane-wave states in two-component discrete Bose-Einstein condensates (BECs). Conditions for the onset of the MI and the respective instability are found analytically. SO coupling allows us to produce the MI even for a small initial wavenumber (q < {\pi}/2) for miscible states. In particular, SO coupling introduces MI even in the absence of hopping coefficient, a concept which may have wider ramifications in heavy atomic BECs. Our investigations predict that the impact of Rabi coupling is more pronounced compared to the other system parameters. We have also shown how our results of the linear stability analysis can be corroborated numerically. The fact that we have brought out the stability criteria in different domains of system parameters means that our model is tailor made experiments.