Nonlinear modes in spatially confined spin–orbit-coupled Bose–Einstein condensates with repulsive nonlinearity

Abstract

It was found that spatially confined spin-orbit (SO) coupling, which can be induced by illuminating Bose-Einstein condensates (BECs) with a Gaussian laser beam, can help trap a spinor Bose gas in multi-dimensional space. Previous works on this topic were all based on a Boson gas featuring an attractive interaction. In this paper, we consider the trapping effect in the case in which the Boson gas features a repulsive interaction. After replacing the repulsive effect, stable excited modes of semi-vortex (SV) type and mixed-mode (MM) type, which cannot be created in a boson gas with attractive interactions, can be found in the current setting. The trapping ability and the capacity of the confined SO coupling versus the degree of the repulsive strength as well as the order of the excited mode are systematically discussed firstly through the paper. Moreover, the stability of the nonlinear mode trapped in this system with a moving reference frame is also discussed. Unlike the system with homogeneous SO coupling, two different types of stationary mobility modes can be stabilized when the SO coupling moves in the x- and y- directions, respectively. This finding indicates that the system with moving confined SO coupling features a typical anisotropic character that differs from the system with moving homogeneous SO coupling.