Laser-assisted coherent atomic tunneling between two trapped Bose-Einsteincondensates

We describe the coherent atomic tunneling between two Bose-Einstein condens ates confined in a double-well potential, whose zero-point energies are mod ulated by a small oscillation of the barrier-laser position. The coupled-mo de equations derived from the Gross-Pitaevskii equation describe the dynami cs in terms of the population imbalance as a function of the modulation amp litude of the zero-point energies normalized by the modulation frequency. I t is predicted that the modulation of the zero-point energies induces the l aser-assisted tunneling (LAT) and the resonant peaks of the LATs are remark ably shifted in energy by the nonlinearity due to the many-body interaction s. It is also shown that the threshold of the nonlinear self-interaction fo r the spontaneous symmetry breaking is modified by the potential modulation s. These features are qualitatively explained by considering that the coupl ing (or tunneling) coefficient K is effectively given by K --> K-n(eff) =J( n)(E-omega/omega)K for the nth LAT under the influence of the potential mod ulations, where E-omega and omega are the modulation amplitude of the zero- point energies and the modulation frequency, respectively. [S1050-2947(99)0 4105-0].