Observation of vortex lattices in Bose-Einstein condensates

Quantized vortices play a key role in superfluidity and superconductivity. We have observed the formation of highly ordered vortex lattices in a rotating Bose-condensed gas. These triangular lattices contained over 100 vortices with Lifetimes of several seconds. Individual vortices persisted up to 40 seconds. The Lattices could be generated over a wide range of rotation frequencies and trap geometries, shedding Light on the formation process. Our observation of dislocations, irregular structure, and dynamics indicates that gaseous Bose-Einstein condensates may be a model system for the study of vortex matter.