Enhanced Excited State Population and Coherence via Adiabatic Tunneling Ionization and Excitation

Ionic coherence created by tunneling ionization and strong-field excitation leads to important ultrafast phenomena such as charge migration and lasing. However, it remains unclear to what extent the coherence can be realistically controlled using strong fields. In this work, an adiabatic excitation regime is identified for a two-level ionic system formed by tunneling, leading to semi-analytical solutions for the ionic population and coherence. It predicts that the excited-state population is enhanced by an order of magnitude, independent of the laser wavelength, while the coherence amplitude can be boosted by about 5 orders of magnitude for a multi-cycle pulse. This work emphasizes the importance of target selection and introduces a theoretical framework for generating and controlling the electronic excited state and coherence using intense laser pulses.