Nonlinear motion of cold atoms in an amplitude modulated standing laser field

Summary form only given. We investigate the nonlinear motion of two-level atoms in an amplitude modulated standing laser field in the limit of large detuning. In this case the center-of-mass-motion is described by the Hamiltonian H(p,q,t)=p/sup 2//2/spl middot//spl kappa/(1/spl middot/2/spl epsiv/sint)cosq, where p and q denote scaled dimensionless momentum and position, t time, and /spl kappa/ and /spl epsiv/ are the parameters defining the depth of the standing wave and the strength of the amplitude modulation, respectively. This system is prominent for proposing the appearance of coherent tunneling between nonlinear resonances of the corresponding classical stroboscopic phase-space map. That means a wave packet initially confined near one such resonance will stay localized and, depending on the modulation parameters will coherently tunnel between delocalized resonances.