ON THE CONTROL OF NONLINEAR-OPTICAL PROCESSES IN STRONG LASER FIELDS

Avoided crossings of quasi-energy levels are one of the most important features of adiabatic approaches to quantum systems. We show that by studying these phenomena we gain deep insight into adiabatic dynamics, allowing one to reveal the mechanisms of non-adiabatic transitions. T hese non-adiabatic processes can be used to populate a desired excited state with significant probabilities and they permit to formulate nec essary conditions for controlling such excitations.