Optical Visibility and Core Structure of Vortex Filaments in a Bosonic Superfluid

We use optical images of a superfluid consisting of a weakly interacting Bose-Einstein condensate of sodium atoms to investigate the structure of quantized three-dimensional vortex filaments. We find that the measured optical contrast and the width of the vortex core quantitatively agree with the predictions of the Gross-Pitaevskii equation.