Stable quantum droplets with higher-order vortex in radial lattices

Abstract

The existence and stability of quantum droplets are studied in ultracold atoms in Bose–Einstein condensates with a radial period lattice under the Lee–Huang–Yang correction. Both stable bell-shaped and ring-shaped zero-vorticity quantum droplets are found in this radial lattice. It is found that the existence curves of the zero-vorticity quantum droplets could violate the V–K criterion, which is a necessary condition to form stable solitons. Under the effect of the radial lattice potential, vortex quantum droplets can be still stable when embedded vorticity S is up to S=10. The vortex quantum droplets can be trapped at the first as well as at the second circular trough of the radial lattice. The stability areas of the vortex quantum droplets with different embedded vorticity S are identified by the long time evolution. The chemical potential of the vortex quantum droplets also violates the V–K criterion. The peak value and effective area of the vortex quantum droplets are independent of the vorticity S, while it only depends on the total norm and the potential of the radial lattice. The double ring quantum droplets, with different embedded vorticity in their inner and outer ring, are also discussed.