Semiclassical dynamics and quantum control in condensed phases: Application to I-2 in a solid argon matrix

A novel scheme is developed which allows for the combination of classical sampling techniques and quantum wave packet dynamics to study both the inhomogeneous structural effects and the homogeneous dynamical effects in condensed phases. We utilize this methodology to theoretically investigate quantum control of the vibrational dynamics of a chromophore embedded in a condensed-phase environment. We consider control of the vibrational dynamics on an excited electronic state of I-2 that has been embedded in a low-temperature argon matrix, to compare with the work of Apkarian, Zadoyan, Martens, and co-workers. The high dimensionality of such systems precludes the possibility of an exact quantum treatment. To overcome this difficulty we take a semiclassical approach using Gaussian wave packet dynamics in the weak response regime. We compare the numerical simulation with experimental pump-probe measurements of Zadoyan and Apkarian, and we find reasonable agreement over the short time interval within which we will attempt to control the vibrational dynamics of the system in this work. Our calculations predict that coherent quantum control is indeed possible in this condensed-phase system at sufficiently short times and provide a measure of how its effectiveness falls off with time in comparison with the parallel gas-phase case. Finally, we summarize some of the conclusions about quantum control which may be drawn from this work and our other theoretical studies of quantum control in condensed-phase environments.