Laboratory conditions in the coherent control of reactive scattering

The principle of controlling atomic and molecular processes via quantum interference, i.e. coherent control, is now well established.1,2 In particular, one arranges to arrive at a Ðnal state through two or more independent coherent routes whose features can be varied via experimentally controllable parameters. Having done so, the multiple routes, and the interference between them, can be controlled by changing the relevant laboratory parameters. Numerous computational and experimental studies show that the interference contribution is a function of the particular product so that one can alter the ratio of products by manipulating the interference contributions through laboratory variables. Further, this control is often found to be extensive. This principle has been established formally and computationally for both unimolecular and bimolecular processes and shown experimentally for unimolecular processes.3h5 A review of this work makes clear, however, that the control of bimolecular processes is still in its infancy. In particular, we have presented the rudiments of a general formalism for control of bimolecular collisions,6h8 studied control for one-dimensional reactive scattering9 and demonstrated control of the di†erential cross section7,8 for isotopic variants of in a particular implementation H] 2 discussed further, below. In this paper we systematically describe the speciÐc requirements for bimolecular control and discuss methods for implementing control in the laboratory. In their most general form they invoke the manipulation of matter as waves, an area overlapping with matter interferometry10 and laser cooling.11 We then consider one simple scenario to examine the extent of possible control. Consider then the general collision processes