Coherent control schemes for the photoionization of helium in the extreme ultraviolet spectral region

Abstract

SynopsisWe present a theoretical study for coherent control based on resonant excitation to doubly excited states of helium. Bichromatic schemes are designed, using XUV light from the seeded free-electron laser FERMI, where the phase of the third harmonic relative to the fundamental can be controlled. In addition to demonstrate the interference effects, we provide detailed theoretical analyses to identify the FEL parameters, such as intensities and pulse durations, needed for experimentally observable coherent control of the photoionization yields.