Control of quantum dynamics by a locally optimized laser field. Multi-photon dissociation of hydrogen fluoride Original Research Article

We present a theoretical method for laser-control of a quantum system with open channels. The framework is based on the local optimization theory proposed in a previous paper (J. Chem. Phys. 100 (1994) 5646). The optimization theory is extended by introducing an optimization parameter q(ϵ) relevant to a continuum channel with kinetic energy ϵ. As an example of application, the control theory is used in multi-photon dissociation of hydrogen fluoride in the ground electronic state. The optimized laser field is analyzed with the help of a window Fourier transform and is shown to approximate a sequence of linear chirped pulses with different chirping rates. Such a form of the optimized laser field originates from the breakdown of the selection rule for optical transition in a Morse oscillator model. The time variation of multi-photon processes in the presence of the optimized laser field and a dissociation fraction are calculated based on the nuclear wave packet theory.