Rossby waves in rapidly rotating Bose–Einstein condensates

Abstract

We predict and describe a new collective mode in rotating Bose–Einstein condensates, which is very similar to Rossby waves in geophysics. In the regime of fast rotation, the Coriolis force dominates the dynamics and acts as a restoring force for acoustic-drift waves along the condensate. We derive a nonlinear equation that includes the effects of both zero-point pressure and inhomogeneity of the gas. It is shown that such waves have negative phase speed, propagating in the opposite sense of the rotation. We discuss different equilibrium configurations and compare them to those resulting from the Thomas–Fermi approximation.