Abstract

We present an experimental demonstration of differential process control in the time domain. In our experiment calcium Rydberg atoms (4sns J = 0) are exposed to a pair of phase-coherent laser pulses (τ_p = 0.4 ps, λ = 393 nm). Each laser pulse performs an “isolated core excitation” (ICE) producing a nonstationary autoionizing wavepacket at an energy just below the Ca⁺ 4p_1/2 ionization limit. Initially a single bound 4p_3/2ns configuration is excited. However, due to the repulsive electron-electron Coulomb interaction, the two valence electrons will eventually scatter into bound 4p_1/2n's channels (configuration interaction) as well as 4s_1/2εl and 3d₃/_2,5/₂εl continuum channels (autoionization). Autoionization into each available continuum channel occurs directly, through the 4p_3/2 channel, and indirectly, through the 4p_1/2 channel. Since the bound character of the nonstationary wavepacket changes as time evolves, the direct and indirect autoionization contributions vary as a function of time, and the electrons ejected into each continuum channel experience time-dependent multiple-path interference.

© 1999 Optical Society of America