Application of ultrashort laser pulses to molecules allows us to control their properties with unrepresented precision. It is clear that by changing the external field one can obtain different evolutions of the system although starting from the same initial condition. The goal of quantum control theory is to find such parameters of a laser field that will drive the quantum evolution of a system to a desired target.
It is a very challenging to synthesize arbitrarily complicated ultrashort laser pulses. Typically, experimental limitations allow us to manipulate only very few parameters of the field with a good enough accuracy. However, it also makes the optimization of such a laser field much easy in numerical sense. Therefore, direct numerical optimization techniques can be used to achieve the required evolution of the system.
One of the most promising approaches which we recently developed consists in splitting the initially prepared ultrashort laser pulse in two identical copies and by varying the time delay between them we can control the evolution of a quantum system. Using a sequence of pulses automatically adds an additional parameter that affects the system evolution, which, in addition, can be very precisely controlled. In this way, the relatively poor accuracy in controlling of other laser pulse parameters will be compensated by adjusting of the time delay.
More detailed description of optimization procedures and several model applications can be found in the following paper.
- Quantum Control with Smoothly Varying Pulses: General Theory and Application to Charge Migration
Journal of Modern Optics, 64 (10-11), 1031 (2017)