Open and closed loop control of complex molecules with shaped fs pulses

Summary form only given. Quantum control of photo induced reactions exploits molecular interferences by adjusting the phases of multiple quantum pathways to different product channels via adapted excitation light. The approach features general applicability but an accurate theoretical prediction of the optimal laserfield to drive a specific chemical reaction is possible only for very basic systems. Moreover, the experimental realization of such a predicted complex field at the site of the interaction volume is extremely difficult or even impossible. If the molecular system under study comprises more than two atoms, a closed loop experiment may bypass such complications since it identifies the optimal pulse shapes in a trial and error fashion, without any specific a priori knowledge. Such a loop is established by a tunable modulator to shape the fs Pulses at will, and a learning algorithm which reads and interprets a relevant response signal to compute a corrective input and return it to the shaper. Many successful demonstrations of this approach on a multitude of atomic and molecular systems have been presented in the last few years. However, in spite of these demonstrations, it was still uncertain whether this approach can be applied to highly complex systems, or even biological samples. The demonstrations illustrate that coherent control effected by a combination of open and closed loop experiments is well suited to uncover the structure and dynamics of complex molecules.