Tunneling Dynamics of Two-Species Bose-Einstein Condensateswith Feshbach Resonances

We investigate tunneling dynamics ofatomic group consisting of three atoms in Bose-Einstein condensates with Feshbach resonance. It is shown that the tunneling of the atom group depends not only on the inter-atomic nonlinear interactions and the initialnumber of atoms in these condensates, but also on the tunneling coupling between the atomic condensate and the three-atomic molecular condensate. It is found that besides oscillating tunneling current between the atomic condensate and the molecular condensate, the nonlinear atomic group tunneling dynamics sustains a self-maintained population imbalance: a macroscopic quantum self-trapping effect. The influence of de-coherence caused by non-condensate atomson the tunneling dynamics is studied. It is indicated that de-coherencesuppresses the atomic group tunneling.