Infinitely-long-range nonlocal potentials and the Bose-Einstein   supersolid phase
  It is shown, with the aid of the Bogoliubov inequality, that a Bose-Einstein condensate has the Bloch form and represents a self-organized supersolid provided the interaction between the condensate atoms is nonlocal and of infinitely long-range. 
Moorad Alexanian
cond-mat.quant-gas