Developments in the Coherent Control of Collisional Processes

Yehiam Prior

Adrien Devolder, Timur V. Tscherbul, Paul W. Brumer

Interference is widely regarded as a foundational attribute of quantum mechanics. However, for a given experimental arrangement, interference can either contribute or not contribute to the outcome depending upon the basis in which it is measured. This observation is both foundational and particularly relevant to coherent control of molecular processes, an approach based upon quantum interference. Here, we address this issue and its relevance to controlling molecular processes via the "coherent control scattering (CCS) matrix," a formalism that allows for an analysis of modifications in an interference structure resulting from a change of basis. This analysis reveals that the change in the interference structure can be attributed to the non-commutativity of the transformation matrix with the CCS matrix and the non-orthogonality of the transformation. Additionally, minimal interference is shown to be associated with the CCS eigenbasis and that the Fourier transform of the eigenvectors of the CCS matrix provides the maximal interference and hence the best coherent control. The change of controllability through a change of basis is illustrated with an example of 85Rb+ 85Rb scattering. In addition, the developed formalism is applied to explain recent experimental results on He + D2 inelastic scattering demonstrating the presence or absence of interference depending on the basis.

Moshe Shapiro, Paul W. Brumer

We review the principles and some recent advances in the theory of coherent control of molecular processes and discuss some of its experimental realizations. Amongst the topics discussed are: bichromatic and pump-dump control; the interference between N-photons and M-photon processes; the optical conversion of a mixture of left- and right-handed chiral molecules into an ensemble containing molecules of the handedness of choice; control of collisional processes; control over chaotic dynamics; effects of decoherence; the solution of the non-degenerate quantum control problem; and control over spontaneous emission and other decay processes.

Ruwang Sung

W. R. Garrett, Yifei Zhu

A well-known quantum interference phenomenon is combined with laser-induced collisional energy transfer to create a coherently controlled excitation involving two species. From one viewpoint the process involves a laser induced catalyst. An experimental demonstration is performed in mixtures of Xe and Kr gases.

Alexei V. Sokolov