Atomic electron wave packets in an electrical field

Abstract
We have observed the periodic motion of a parabolic electron wave packet. The wave packet was created by coherent excitation with 7-ps laser pulses of several parabolic states of atomic rubidium in a dc electrical field. The dispersion of the wave packet was small because the spacing between subsequent energy levels of the Stark map is almost constant. By measuring the photoionization yield in a pump-probe experiment, as many as 10 oscillations were observed.