Bose fluids above T(c): incompressible vortex fluids and "supersolidity"

This Letter emphasizes that nonlinear rotational or diamagnetic susceptibility is characteristic of Bose fluids above their superfluid T(C)'s. For sufficiently slow rotation or, for superconductors, weak B fields, this amounts to an incompressible response to vorticity. The cause is that there are terms missing in the conventionally accepted model Hamiltonian for quantized vortices in the Bose fluid. The resulting susceptibility can account for recent observations of Chan et al. [Nature (London) 427, 225 (2004); Science 305, 1941 (2004)] on solid He and Ong et al. [Europhys. Lett. 72, 451 (2005) on cuprate superconductors.