Vortex lines and vortex lattices in a Bose-Einstein condensate

Summary form only given. We have recently developed an evaporative cooling technique that simultaneously accelerates the rotation of an ultracold /sup 87/Rb gas. As a normal gas is evaporatively spun up and cooled below quantum degeneracy, it is found to nucleate vorticity in a BEC. With this method, condensates are readily formed with a wide range of vorticity, ranging from single vortex lines to large lattices consisting of 65 vortices or more. In the presence of such large lattices, the condensate exhibits considerable centrifugal distortion. From the degree of the condensate´s distortion, effective rotation rates of up to 95% of the centrifugal limit are inferred. Experiments are described which elucidate the life-cycle and behaviour of rotating condensates. Of particular interest is the identification of vortex nucleation and decay mechanisms.