Real-Time Observation of Electron-Hole Coherence Induced by Strong-Field Ionization

Abstract

We introduce and demonstrate a new approach to measure the electron-hole dynamics and coherence induced by strong-field ionization using hole-assisted high-harmonic spectroscopy. The coherent driving of the infrared and XUV pulses correlates the dynamics of the core-hole and the valence-hole by coupling multiple continua, which leads to the otherwise forbidden absorption and emission of high harmonics. An analytical model is developed based on the strong-field approximation by taking into account the essential multielectron configurations. The emission spectra from the core-valence transition and the core-hole recombination are found to modulate strongly as functions of the time delay between the two pulses, suggesting that the coherent electron wave packets in multiple continua can be utilized to temporally resolve the core-valence transition in attoseconds.