Inter-Condensate Tunneling in Bose-Einstein Condensates with Feshbach   Resonances
  Recently, effects of Feshbach resonances in atom-atom interactions were observed by varying the external magnetic field of an atomic Bose-Einstein condensate (BEC). We point out that the quasi-bound molecules created in the intermediate state of the resonance can form a second, molecular condensate. The many-body state of the system is then a hybrid atomic/molecular condensate with inter-condensate tunneling of atom pairs. A sudden variation of the magnetic field results in oscillations of the number of atoms and molecules in their respective condensates, providing a signature of this novel type of quantum tunneling. 
Eddy Timmermans, Paolo Tommasini, Robin Cote, Mahir Hussein and Arthur   Kerman