Matter-waves in Bose-Einstein condensates with spin-orbit and Rabi couplings

TL;DR

This paper derives effective 1D and 2D equations for spin-orbit and Rabi coupled Bose-Einstein condensates from 3D models, revealing how these couplings influence localized solutions and stability.

Contribution

It introduces nonpolynomial Schrödinger equations for BECs with spin-orbit and Rabi couplings, derived from 3D theory, and explores their localized solutions and stability.

Findings

SO and Rabi couplings create sidelobes in density profiles.

Localized solutions exist for both repulsive and attractive interactions.

Increasing SO coupling can destabilize attractive condensates.

Abstract

We investigate the one-dimensional (1D) and two-dimensional (2D)reduction of a quantum field theory starting from the three-dimensional (3D) many-body Hamiltonian of interacting bosons with spin-orbit (SO) and Rabi couplings. We obtain the effective time-dependent 1D and 2D nonpolynomial Heisenberg equations for both repulsive and attractive signs of the inter-atomic interaction. Our findings show that in case in which the many-body state coincides with the Glauber coherent state,the 1D and 2D Heisenberg equations become 1D and 2D nonpolynomial Schr\"odinger equations (NPSEs). These models were derived in a mean-field approximation from 3D Gross-Pitaevskii equation (GPE), describing a Bose-Einstein condensate (BEC)with SO and Rabi couplings. In the present work self-repulsive and self-attractive localized solutions of the 1D NPSE and the 1D GPE are obtained in a numerical form. The combined action of SO and Rabi couplings produces conspicuous sidelobes on the density profile, for both signs of the interaction. In the case of the attractive nonlinearity, an essential result is the possibility of getting an unstable condensate by increasing of SO coupling.