Time-resolved configuration interaction

Using the optical Ramsey method we have observed the configuration interaction in Ba drive atoms back and forth between the doubly excited 5d7d state and the degenerate 6snd Rydberg states. Our observations can be understood qualitatively as autoionization of the initially excited 5d7d state into the Rydberg states, followed by capture of the Rydberg electron by the ion a Kepler time later. After a time delay, the whole process repeats. A quantum defect theory description provides a quantitative picture and clarifies the connection to resonance scattering.