Indian Inst Technol, Dept Phys, Gauhati 781039, Assam - India
 Bharathidasan Univ, Dept Phys, Tiruchirappalli 620024, Tamil Nadu - India
 Univ Sao Paulo, Inst Fis, BR-05508090 Sao Paulo - Brazil
Total Affiliations: 3
Physical Review A;
NOV 17 2021.
Web of Science Citations:
We present the collective excitation spectrum analysis of binary Bose-Einstein condensates (BECs) with spinorbit (SO) and Rabi couplings in a quasi-two-dimensional system. In particular, we investigate the role of SO and Rabi coupling strengths in determining the dynamical stability of the coupled BECs using Bogoliubov-de Gennes (BdG) theory. Using the eigenenergy of the BdG spectrum, we confirm the existence of phonon, roton, and maxon modes with weak repulsive intra- and interspecies contact interactions. The depth of the minimum corresponding to the roton mode strongly depends on the coupling strength. We find that the increase of the SO coupling leads to instability, while the increase in the Rabi coupling stabilizes the system. Also, the eigenvectors of the BdG spectrum indicate the presence of a densitylike mode in the stable regime and spinlike modes in the unstable regimes. A phase diagram demonstrating the stability regime in the plane of SO and Rabi coupling strengths is obtained. Finally, we complement the observation of the excitation spectrum with the direct numerical simulation results of coupled Gross-Pitaevskii equations. (AU)