Investigation of the ionization of atom driven by a few-cycle laser pulse in phase space

Abstract

We perform a comprehensive study of the ionization of hydrogen atom by a few-cycle laser pulse with a fixed carrier-envelop in phase space through calculating the Wigner functions. The results show that the electrons always locate around the nucleus before the laser electric field force reaches a certain intensity. While as the force of the laser electric field increases, the electrons are gradually deviated away from the nucleus. The ionized electrons are driven back to the core region and make a wiggling motion because of the variation of the laser electric field force with time. Moreover Wigner functions enable us to clearly show the classical and quantum behaviours during ionization process are presented in phase space, and explicitly attribute the arc fringes to the interference effect between the electronic wavepackets born at different ionization times.