Prof. Dr. Tilmann Kuhn

Institut für Festkörpertheorie Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-Str. 10 48149 Münster

Tel: 0251/83-36312 Fax: 0251/83-33669 Email: Tilmann.Kuhn@uni-muenster.de

Dr. Vollrath Martin Axt

Institut für Festkörpertheorie Westfälische Wilhelms-Universität Münster Wilhelm-Klemm-Str. 10 48149 Münster

Tel: 0251/83-39130 Fax: 0251/83-33669 Email: AxtVM@uni-muenster.de

Ultrafast manipulation and quantum kinetics of spin decoherence in magnetic quantum dots

The main goal of this project is the theoretical analysis of the possibilities to manipulate on short time scales the spin of a single Mn atom embedded in a quantum dot by means of suitably designed pulsed laser excitations. Such coherent control processes are deteriorated by decoherence mechanisms, such as the spin decoherence due to the combination of spin-orbit, exchange, and carrier-phonon interactions. These decoherence processes shall be modelled on a quantum kinetic level which automatically satisfies all fundamental quantum mechanical uncertainties. In particular the strict energy selectivity, which is a basic ingredient of Fermi�s golden rule, does not hold in the quantum kinetic regime due to the energy time uncertainty. The resulting quantum kinetic energy broadening is expected to be relevant especially for the present system leading to qualitative modifications of the dynamics. Furthermore the quantum kinetic theory is also able to account for the fact that in certain cases decoherence processes in quantum dot systems result only in a partial loss of coherence which could open new perspectives for the coherent control of spin decoherence.