Ionization of He by ultrastrong single-cycle pulses.

Recently, the progress of experimental techniques has allowed the realization of less-than-a-cycle pulses. Though these pulses are as yet too weak to ionize atoms from the ground state, the rapid progress in experimental methods warrants the investigation of possibilities opened up by these new achievements. In this paper we use the quasiclassical Fermi molecular-dynamics method to study the dynamics of ionization and the electron correlations of initially ground-state He atoms in single-cycle infrared pulses. An interpretation is also made in terms of a quasistatic ionization model.