EXCITED HYDROGEN-ATOMS IN PULSED MICROWAVES - JOURNEYS TO QUANTUM CHAOS AND BACK

Recent ''one-dimensional'' experiments on hydrogen in microwaves have provided evidence for nonadiabatic transition processes occurring during the rise and fall of a short pulse of strong microwave electric field. Quantum coupling near a level crossing of pairs of quantum eigenstates has been observed to produce transition probabilities exhibiting a classical scaling. Separatrix crossing effects produce near classical, double peaked, experimental final bound state distributions. Some evidence is presented that level crossing and separatrix crossing sometimes can be related. The present system seems useful in the development of the quantum description of near-classical dynamical processes, in terms of the classical character of individual semiclassical eigenstates and the couplings within sets of such states.