Higher-charged binary vortex quantum droplets in a ring potential

Abstract

We investigate the stability and characteristics of vortex quantum droplets (QDs) with particle imbalance and different topological charges $S_{\pm }$ in two components formed by binary Bose–Einstein condensates trapped in a ring potential. Two types of binary vortex QDs including semi-vortex (SV) and mixed-vortex (MV) QDs can be stable up to at least $S_{-}=14$ with the help of the ring potential. It is worth noting that, for a given number of particles in the binary vortex QDs, the more particles are concentrated in the zero-vorticity and lower-vorticity components for stable SV and MV QDs, respectively, and the imbalanced degree is further increased with the growth of topological charge $S_{-}$. We found that the relative norm (scaled number of particles) distribution of two components in imbalanced SV and MV QDs with high topological charge can be controlled by adjusting the ring potential radius, width, and depth. In addition, it is revealed that stable binary vortex QDs in the ring potential can violate the Vakhitov-Kolokolov criterion. Effects of the topological charges $S_{\pm }$ and the ring potential parameters on the chemical potential and the peak density of the SV and MV QDs are systematically studied. The stability areas of the SV and MV QDs with different topological charges in the plane of the total norm and coupling constant are also identified. The results may be relevant to design an encoding device employing binary vortex QDs with different topological charges for storing different data components.