Influence of optical and interaction-induced dephasing effects on the short-pulse ionization of atomic gases

The ionization dynamics of dilute atomic gases induced by ultra-short high-intensity optical-pulse excitation is treated fully microscopically. The optical excitation is self-consistently coupled to the many-body interactions of the electrons, including their interactions with free electrons, ions, and neutral atoms. The theory is numerically evaluated for the example of a gas of hydrogen atoms for a broad range of pulses covering the tunnel ionization, multi-photon ionization, as well as the one-photon ionization regimes. It is shown that the many-body effects during the excitation distinctly influence the atomic ionization dynamics. The ionization degree after the pulse is dominated by the dephasing caused by the excitation-dependent interplay between the purely optical processes and the many-body interactions.