Kicked Rydberg atom: Response to trains of unidirectional and bidirectional impulses - art. no. 043402

The behavior of Rb(390p) atoms subject to a train of up to 50 half-cycle pu lses (HCPs) with duration T-p << T-n, where T-n is the classical electron o rbital period, is investigated. In this limit, each HCP simply delivers an impulsive momentum transfer or "kick'' to the electron. The response of ato ms to a series of unidirectional kicks and to a series of kicks that altern ate in direction is compared. For unidirectional kicks, the Rydberg atom su rvival probability has a pronounced maximum when the pulse repetition frequ ency v(p) is similar to 1.3 times the classical orbital frequency v(n). Cla ssical simulations show this behavior provides a signature of dynamical sta bilization. Evidence of dynamical stabilization and chaotic diffusion is al so found in the distribution of final bound states. Very different behavior is observed for alternating kicks. The survival probability generally incr eases with v(p), although a small local maximum is evident when v(p)similar to v(n) Little evidence of dynamical stabilization is observed in either t he calculated dependence of the survival probability on the number of appli ed kicks, in the measured final bound-state distribution, or in the classic al phase space of the kicked atom. Model calculations for a one-dimensional "atom" reveal islands of stability, but their three-dimensional counterpar ts are found to be unstable.