Non-Hermitian Floquet dynamics of argon atoms at 248 nm

We present ab initio calculations for argon in a KrF laser field for intensities up to around 10(14) W cm(-2). We study the dynamics of Floquet field-atom states in laser pulses with time-varying amplitudes. We show how the pulse length and shape can be used together with knowledge of the Floquet states and quasienergies to control directly the atomic populations both during and at the end of the pulse. The calculations describe experimentally viable coherent control methods and the analysis is applicable to other field-atom systems. These are the first such ab initio calculations that we are aware of for a many-electron system.