Coherence-manipulation of an atomic wave packet via electron-electron correlations

An electronic wave packet is excited in the Rydberg states of atomic calciu m. The strong excitation of the remaining valence electron modifies the par ticular coherent superposition state associated with this Rydberg wave pack et due to the electron-electron correlation. This modification is observed by a coherent pump-probe measurement in which the change of the global phas e of the wave packet with respect to a local oscillator is found. The magni tude of the electron-electron correlation is varied experimentally and lead s to sharp resonances in the phase. The coherence is maintained despite the open autoionization channel. The process also allows the manipulation of i ndividual states within the wave packet. (C) 1999 Optical Society of Americ a.