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O: Fachverband Oberflächenphysik

O 7: Surface Dynamics I

O 7.6: Talk

Monday, March 14, 2011, 12:30–12:45, WIL C107

Optimal control of open quantum systems applied on photochemistry on surfaces — Erik Asplund and •Thorsten Klüner — Carl von Ossietzky Universität Oldenburg, Germany

A quantum system in condensed phase, which undergoes strong dissipative processes, is an open quantum system. From the theoretical viewpoint it is important to model open quantum systems in a rigorous way. The description of open quantum systems can be realized within the ``Surrogate Hamiltonian'' approach, which is a non-Markovian approach. In the ``Surrogate Hamiltonian'' approach, a quantum system is separated into a primary system and a bath. Besides the traditional formulation of dissipative processes through the spectral density, the ``Surrogate Hamiltonian'' method enables a microscopic description of excitation and relaxation process for open quantum systems.

Light interacting with atoms and molecules is not only a source of information about the atoms and molecules studied, it can also initiate charge and energytransfer processes, i.e. manipulate the evolution of the molecules studied. A theoretical tool for the design of laser pulses to transfer an initial state to a final state is optimal control theory (OCT). Besides the traditionalfinal-time control algorithms, there exist methods to also handle time-dependent control targets. In this talk, OCT with time-dependent targets is combined with the ``Surrogate Hamiltonian" method in order to gain control of dissipative quatum systems. Two model systems representing adsorbate-surface systems will be presented and the controllability of the systems will be discussed.