Macroscopic quantum tunneling and resonances in coupled Bose-Einstein condensates with oscillating atomic scattering length

We study the macroscopic quantum tunneling, self-trapping phenomena in two weakly coupled Bose-Einstein condensates with periodically time-varying ato mic scattering length. The resonances in the oscillations of the atomic populations are investigat ed. We consider oscillations in the cases of macroscopic quantum tunneling and the self-trapping regimes. The existence of chaotic oscillations in the relative atomic population due to overlaps between nonlinear resonances is showed. We derive the whisker-type map for the problem and obtain the esti mate for the critical amplitude of modulations leading to chaos. The diffus ion coefficient for motion in the stochastic layer near separatrix is calcu lated. The analysis of the oscillations in the rapidly varying case shows t he possibility of stabilization of the unstable pi-mode regime. (C) 2000 Pu blished by Elsevier Science B.V. PACS: 03.75.Fi; 05.30.Jp.