RECURRENCE SPECTROSCOPY OF A TIME-DEPENDENT SYSTEM - A RYDBERG ATOM IN AN OSCILLATING FIELD

We report the results of an experimental and theoretical investigation of the recurrence spectra of Rydberg atoms in a static plus weak osci llating electric field. Experiments reveal the systematic weakening of orbits in a recurrence spectrum as the oscillating field strength and frequency are changed. We describe a generalization of closed orbit t heory to time-dependent systems and show that it provides a qualitativ e and quantitative description of the phenomena.