A Novel Mechanism for Superfluidity Breakdown in Weakly Coupled   Bose-Einstein Condensates
  This paper has been withdrawn by the authors. The authors have now written two separate papers, one theoretical (A. Smerzi, A. Trombettoni, P. G. Kevrekidis, and A. R. Bishop Phys. Rev. Lett. 89, 170402 (2002)) and one experimental (F. S. Cataliotti, L. Fallani, F. Ferlaino, C. Fort, P. Maddaloni, and M. Inguscio New Journal of Physics 5, 71 (2003)). 
F. S. Cataliotti, L.Fallani, F. Ferlaino, C. Fort, P. Maddaloni,   M.Inguscio, A. Smerzi, A. Trombettoni, P. G. Kevrekidis, ...