Feshbach-resonance-induced atomic filamentation and quantum pair   correlation in atom-laser-beam propagation
  We study the propagation of an atom laser beam through a spatial region with a magnetic field tuned to a Feshbach resonance. Tuning the magnetic field below the resonance produces an effective focusing Kerr medium that causes a modulational instability of the atomic beam. Under appropriate circumstances, this results in beam breakup and filamentation seeded by quasi-particle fluctuations, and in the generation of correlated atomic pairs. 
Weiping Zhang, Chris P. Search, Han Pu, Pierre Meystre, Ewan M. Wright