Dynamic stabilization of ground-state hydrogen in superintense laser pulses of finite duration

We present a comprehensive calculation of 3D dynamic stabilization (DS) of ground-state hydrogen in superintense laser pulses of finite duration, with cos² envelope. The ionization probability at the end of the pulse was calculated for a range of frequencies w from 0.8 to 8 a.u., for peak fields ranging up to 80 a.u. (depending on w), and for pulse lengths t extending from 1 to 400 cycles (depending on w). We find prominent DS and substantial atomic survival under conditions where our nonrelativistic, dipole approximation calculation is expected to be valid. The connection of our results with other theories is analyzed. Thus, we find that the evolution of the atom is adiabatic and amenable to single-state Floquet theory, up to very large peak fields of several atomic units, and down to very short femtosecond pulses. In the general case, however, a unitary description of the ionization process, and DS in particular, requires “multistate Floquet theory.” Our results favor the possibility of observing DS experimentally with the new VUV-FEL light sources that are now in test operation or construction, or with the attosecond pulses that have been obtained from high harmonic generation.