The stability of nonequilibrium polariton superflow in the presence of a   cylindrical defect
  We make a theoretical study of the stability of nonequilibrium polariton superflows that interact with a cylindrical defect. The nonresonantly pumped polariton condensate is modelled with a generalized complex Ginzburg-Landau equation. At low pump intensities the dissipation is found stabilize the superflow. At large pump intensities, we find an instability that sets a lower critical speed for superfluidity. For even larger pump power, the lower and upper critical speed meet and stable superflows are no longer possible. 
Michiel Wouters
cond-mat.other