Capillary Flotation in a System of Two Immiscible Bose-Einstein Condensates

A spatially inhomogeneous, trapped two-component Bose-Einstein condensate of cold atoms in the phase separation mode has been numerically simulated. It has been demonstrated for the first time that the surface tension between the components makes possible the existence of drops of a denser phase floating on the surface of a less dense phase. Depending on the harmonic trap anisotropy and other system parameters, a stable equilibrium of the drop is achieved either at the poles or at the equator. The drop flotation sometimes persists even in the presence of an attached quantized vortex.