Berlin 2005 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 12: Quantenpunkte und -dr
ähte: Optische Eigenschaften II
HL 12.1: Vortrag
Freitag, 4. März 2005, 15:00–15:15, TU P-N201
Biexciton Rabi oscillations in a single InGaAs/GaAs quantum dot — •Stefan Stufler1, P. Ester1, A. Zrenner1, P. Machnikowski2, V. M. Axt2, T. Kuhn2, and M. Bichler3 — 1Universität Paderborn, Warburger Straße 100, D-33098 Paderborn, Germany — 2Institut für Festkörpertheorie, Westfälische Wilhelms-Universität, 48149 Münster, Germany — 3Walter Schottky Institut, Technische Universität München, Am Coulombwall, D-85748 Garching, Germany
We report coherent control of the ground state biexciton in a single InGaAs/GaAs quantum dot. Excitation is achieved by resonant two-photon absorption of ps laser pulses. The occupancy of the quantum dot then is measured via the photocurrent. We observe Rabi oscillations which, in contrast to single-exciton oscillations, are not purely sinusoidal in excitation amplitude. This behavior is due to the two-photon excitation process. The experimental data show good qualitative agreement to theoretical curves derived for the assumption that sequential creation of the individual excitons is negligible. We have furthermore investigated the phase stability of coherent superposition states by quantum interference experiments. The observed dephasing times are only slightly shorter than those in according single exciton measurements. We thus are able to prove the feasibility of quantum gates based on the biexciton energy renormalization.