OBSERVATION OF QUASI-LANDAU WAVE-PACKETS

Atomic wave packets are produced in strong magnetic fields by exciting rubidium atoms with a short UV laser pulse. The strength of the magnetic field is varied from 0 to 3.3 T. In a classical model of these Rydberg atoms, this variation leads to a progression of the system from a regime of regular motion to one where chaotic motion dominates. The evolution of the wave packet is observed using a phase-sensitive technique and is compared to the predictions of a semiclassical model. The effect of an electric field, applied parallel to the magnetic field, is also studied. As the electric field is increased, significant changes occur that are due in part to the appearance of new orbits.