Systems of vortices in a binary core–shell Bose–Einstein condensate

A trapped Bose–Einstein-condensed mixture of two types of cold atoms with significantly different masses has been simulated numerically within the coupled Gross–Pitaevskii equations. A configuration consisting of a vortex-free core and a shell penetrated by quantum vortices is possible in the phase separation regime. The dynamic properties of vortices in the shell are determined by several parameters. Physically implementable parametric domains corresponding to long-lived strongly nonstationary systems of several vortices attached to the core have been sought. A number of realistic numerical examples of three vortex pairs existing for many hundreds of characteristic times have been presented.