Vortex gap solitons in spin-orbit-coupled Bose-Einstein condensates with competing nonlinearities

TL;DR

This paper explores the formation, stability, and dynamics of full vortex gap solitons in spin-orbit-coupled Bose-Einstein condensates with competing nonlinearities, revealing stable states with different effective masses near the bandgap edges.

Contribution

It demonstrates the existence of stable full vortex gap solitons with vorticity in both components, a novel finding in SOC BEC systems with competing nonlinearities, contrasting previous semi-vortex states.

Findings

Stable FVGS states exist with positive or negative effective mass.

FVGS stability depends on the type of nonlinearities (cubic and quintic).

Mobility and collision behaviors of FVGSs are characterized.

Abstract

The formation and dynamics of full vortex gap solitons (FVGSs) is investigated in two-component Bose-Einstein condensates with spin-orbit coupling (SOC), Zeeman splitting (ZS), and competing cubic and quintic nonlinear terms, while the usual kinetic energy is neglected, assuming that it is much smaller than the SOC and ZS terms. Unlike previous SOC system with the cubic-only attractive nonlinearity, in which solely semi-vortices may be stable, with the vorticity carried by a single component, the present system supports stable FVGS states, with the vorticity present in both components (such states are called here full vortex solitons, to stress the difference from the half-vortices). They populate the bandgap in the system's linear spectrum. In the case of the cubic self-attraction and quintic repulsion, stable FVGSs with a positive effective mass exist near the top of the bandgap. On the contrary, the system with cubic self-repulsion and quintic attraction produces stable FVGSs with a negative mass near the bottom of the bandgap. Mobility and collisions of FVGSs with different topological charges are investigated too.