Superfluid behavior of a Bose-Einstein condensate in a random potential
  We investigate the relation between Bose-Einstein condensation (BEC) and superfluidity in the ground state of a one-dimensional model of interacting Bosons in a strong random potential. We prove rigorously that in a certain parameter regime the superfluid fraction can be arbitrarily small while complete BEC prevails. In another regime there is both complete BEC and complete superfluidity, despite the strong disorder. 
M. K\"onenberg (Memorial University), T. Moser (University of Vienna),   R. Seiringer (Institute of Science and Technology A...
cond-mat.quant-gas math-ph math.MP