Quantum-state measurement of ionic Rydberg wavepackets

Nearly unipolar, sub-picosecond half-cycle pulses (HCPs) have been used to measure, via impulsive ionization, the aspects of the electronic quantum state relevant to the radial motion of Ba+ ng Rydberg wavepackets. Following laser excitation of the ionic wavepacket, the double ionization probability is measured as a function of the amplitude and delay of the HCP probe. Fourier transform of the time-dependent ionization signal facilitates the determination of the complex amplitudes of the constituent ng eigenstates in the wavepacket, enabling a full characterization of its time-dependent radial evolution. This is the first experimental demonstration of wavepacket recovery in ions, a capability that may prove to be invaluable for future measurements of quantum dynamics in multielectron systems.