Tunneling dynamics of Bose-Einstein condensates with Feshbach resonances

We study tunneling dynamics of atomic pairs in Bose-Einstein condensates with Feshbach resonances. It is shown that the tunneling of the atomic pairs depends on not only the tunneling coupling between the atomic condensate and the molecular condensate, but also the interatomic nonlinear interactions and the initial number of atoms in these condensates. It is found that in addition to oscillating tunneling current between the atomic condensate and the molecular condensate, the nonlinear atomic-pair tunneling dynamics sustains a self-locked population imbalance: a macroscopic quantum self-trapping effect. The influence of decoherence induced by noncondensate atoms on the tunneling dynamics is investigated. It is shown that decoherence suppresses atomic-pair tunneling.