Zero-temperature damping of Bose-Einstein condensate oscillations by vortex-antivortex pair creation

We investigate vortex-antivortex pair creation in a supersonically expanding and contracting quasi-two-dimensional Bose-Einstein condensate at zero temperature. For sufficiently large-amplitude condensate oscillations, pair production provides the leading dissipation mechanism. The condensate oscillations decay in a nonexponential manner, and the dissipation rate depends strongly on the oscillation amplitude. These features allow one to distinguish the decay due to pair creation from other possible damping mechanisms. An experimental observation of the predicted oscillation behavior of the superfluid gas provides a direct confirmation of the hydrodynamical analogy of quantum electrodynamics and quantum vortex dynamics in two spatial dimensions.