Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 85: Poster Session II
HL 85.100: Poster
Donnerstag, 17. März 2011, 18:00–21:00, P4
Effects of phonon-induced dephasing on Rabi oscillations in GaAs quantum dots — •Sebastian Lüker1, Doris Reiter1, Vollrath Martin Axt2, and Tilmann Kuhn1 — 1Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster — 2Theoretische Physik III, Universität Bayreuth, 95440 Bayreuth
We discuss the laser-induced Rabi oscillation of the exciton occupation in a GaAs quantum dot (QD). Considering the strong confinement limit we model the QD as a two level system. In principle arbitrary superpositions of these two states can be prepared by using light-induced Rabi oscillations. However, the control of the quantum state is limited by dephasing caused by electron-phonon interaction which reduces the coherence of the system and leads to a damping of the Rabi oscillations. Due to the energy structure only phonon-induced pure dephasing is taken into account. We study the impact of the dephasing on the coherence in the density matrix formalism. The many body nature of the problem leads to an infinite hierarchy of equations of motion which we truncate by a correlation expansion. The resulting closed set of equations is solved numerically. The influence of the different orders of this hierarchy is discussed. Recent experiments on Rabi oscillations in semiconductor QDs have been performed showing damped Rabi oscillations in the occupation of the QD exciton state [Ramsey et al., PRL 105, 177402 (2010)]. We compare our model with the experimental data and find a very good qualitative and quantitative agreement.