  We consider superfluidity and quantum vorticity in rotating spacetimes. The
system is described by a complex scalar satisfying a nonlinear Klein-Gordon
equation. Rotation terms are identified and found to lead to the transfer of
angular momentum of the spacetime to the scalar field. The scalar field
responds by rotating, physically behaving as a superfluid, through the creation
of quantized vortices. We demonstrate the vortex nucleation through numerical
simulation.
