Understanding learning control in a molecular family

Experiments demonstrate coherent control over a wide variety of atomic and molecular systems using shaped ultrafast laser pulses. In many cases, where the system Hamiltonian is not known well enough to predict optimal control fields a priori, learning algorithms are used. Although learning algorithms are successful at discovering optimal laser pulses for control, it is generally difficult to understand the physical mechanisms underlying control. Although a few pioneering experiments have been able to uncover the control mechanism exploited by an optimal pulse, the lack of systematic techniques to gain insights into control mechanisms and to develop predictive models for control remains a significant barrier to achieving the ultimate goal of laser selective chemistry. This chapter uses a combination of learning algorithm modifications, pump-probe spectroscopy, ab initio molecular structure calculations, and quasi-static molecular ionization calculations to decipher the mechanism underlying control in l, l, l-trifluoroacetone. This predicts control in similar molecules such as tri-deuterated acetone and 1,1,1-trichloroacetone.