Two-dimensional composite solitons in Bose-Einstein condensates with spatially confined spin-orbit coupling

TL;DR

This paper investigates the formation and stability of two-dimensional composite solitons in Bose-Einstein condensates with spatially confined spin-orbit coupling, identifying the minimum confinement needed for stable solitons.

Contribution

It introduces a novel analysis of 2D solitons with spatially confined spin-orbit coupling using numerical and variational methods, revealing stability conditions.

Findings

Identified minimum spatial confinement for stable solitons.

Constructed families of semi-vortex and mixed-mode solitons.

Demonstrated stability of solitons under confined spin-orbit coupling.

Abstract

It was recently found that the spin-orbit (SO) coupling can help to create stable matter-wave solitons in spinor Bose-Einstein condensates in the two-dimensional (2D) free space. Being induced by external laser illumination, the effective SO coupling can be applied too in a spatially confined area. Using numerical methods and the variational approximation (VA), we build families of 2D solitons of the semi-vortex (SV) and mixed-mode (MM) types, and explore their stability, assuming that the SO-coupling strength is confined in the radial direction as a Gaussian. The most essential result is identification, by means of the VA and numerical methods, of the minimum size of the spatial confinement for which the 2D system maintains stable solitons of the SV and MM types.