Analytical coherent controls of Alkali atoms in strong field regime

Abstract

The outcome of quantum-mechanical dynamics can be steered by application of light field shaping, and this concept is called "Coherent Quantum Control." Since Silberberg`s seminal work of the coherent control of two-photon absorption process of atomic Cesium, many studies on the coherent control of multi-photon processes have been attempted in more complex systems. But these studies considered multi-photon processes in weak-field regime, where the energy level structure remains unchanged during the light-matter interaction. Recent studies are focused on coherent control in strong-field regime. The strong-field effects in a multi-photon process, such as dynamic Stark shift and power broadening, prevent efficient coupling of matter with an intense femtosecond laser field. Especially, the dynamic Stark shift is crucial to optimize multi-photon processes.

Hence we have developed a new coherent control method, in which the dynamic Stark shift is successfully compensated. In this thesis, we present experimental demonstration of the newly devised analytical coherent control method, in which the laser-induced energy level change is compensated by the frequency-shift of computer-programmed shaped laser pulses. In the newly developed analytical coherent control, laser pulses are shaped as a polynomial sum of frequency and/or time in an acousto-optic programmable dispersive filter. For the given light-matter interactions, the model Hamiltonians developed in the strong-field regime are analytically studied and the derived excitation probability formulas given as analytical solutions are compared with the experimental results.

In experiments with atomic Cesium, we have demonstrated the analytical coherent control of the two-photon absorption in a dynamically shifted energy level structure. We have obtained the transition probability of the two-photon broadband excitation as a function of pulse shape parameters, frequency detuning, and laser intensity, by solving the two-ph...