Very-high-n Stark wave packets generated by an electric-field step

Abstract

Wave packets comprising a coherent superposition of n\ensuremath{\simeq}390 Stark states have been created in potassium by rapid application of a dc field. Their properties are examined using a half-cycle probe pulse that is applied following a variable time delay and that ionizes a fraction of the excited atoms. The survival probability exhibits pronounced oscillations (quantum beats) that are associated with the time evolution of the wave packet. Interestingly, even in the present regime of complete overlap of different Stark manifolds, a single dominant beat frequency is observed, and this is explained quantum mechanically in terms of energy-level statistics. Similar behavior is predicted by classical trajectory Monte Carlo simulations that reproduce well the experimental observations demonstrating classical-quantum correspondence in high-n systems.