Dissipationless flow and superfluidity in gaseous Bose-Einstein   condensates
  We study dissipation in a dilute Bose gas induced by the motion of a macroscopic object. A blue-detuned laser beam focused on the center of a trapped gas of sodium atoms was scanned both above and below the BEC transition temperature. The measurements allow for a comparison between the heating rates for the superfluid and normal gas. 
C. Raman, R. Onofrio, J. M. Vogels, J. R. Abo-Shaeer, and W. Ketterle