Ground-state multiquantum vortices in rotating two-species superfluids

Abstract

We show numerically that a rotating, harmonically trapped mixture of two Bose-Einstein-condensed superfluids can---contrary to its single-species counterpart---contain a multiply quantized vortex in the ground state of the system. This giant vortex can occur without any accompanying single-quantum vortices, may either be coreless or have an empty core, and can be realized in a $^{87}\mathrm{Rb}\text{\ensuremath{-}}^{41}\mathrm{K}$ Bose-Einstein condensate. Our results not only provide a rare example of a stable, solitary multiquantum vortex but also reveal exotic physics stemming from the coexistence of multiple, compositionally distinct condensates in one system.