Alkali Bose Condensate Mixtures

We show that binary mixtures of Bose-condensates of alkali atoms have a great variety of ground state and vortex structures which can be accessed experimentally by varying the particle numbers of different alkalis. We have constructed a simple algorithm to determine the density profiles of these states, and have worked out their phase diagrams within Thomas-Fermi approximation. Many structures of the alkali binary contain a coexisting region, which is the analog of the long sought $^{3}$He-$^{4}$He interpenetrating superfluids in ultra-low temperature physics.