Model study of coherent-control of the femtosecond primary event of vision

A bichirped coherent-control scenario is introduced and implemented in a model study of coherent-control of the cis/trans photoisomerization of the retinal chromophore in rhodopsin. The approach involves selective photoexcitation of multiple vibrationally coherent wave packets by using two chirped femtosecond pulses. Control over product yields at finite time after photoexcitation of the system is achieved by externally changing the relative phases of the photoexcitation pulses and consequently affecting the interference phenomena between individual wave packet components. Furthermore, a measure of decoherence associated with the underlying quantum reaction dynamics is computed. Extensive coherent-control over transient populations is predicted, despite the ultrafast decoherence phenomena induced by the vibronic activity, providing results of broad theoretical and experimental interest.