Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 59: Quantum Dots and Wires, Optical Properties V
HL 59.4: Vortrag
Donnerstag, 25. März 2010, 16:45–17:00, H14
Coherent spectroscopy of single GaAs/AlGaAs quantum dots — •Christian Wolpert1,2, Lijuan Wang3, Paola Atkinson3, Armando Rastelli3, Oliver G. Schmidt3, and Markus Lippitz1,2 — 1Max-Planck Institut für Festkörperforschung, Stuttgart, Germany — 24. Physikalisches Institut, Universität Stuttgart, Germany — 3Institut für Integrative Nanowissenschaften, IFW Dresden, Germany
Semiconductor quantum dots (QDs) are a promising candidate for the realization of qbits for quantum computation. With coherence times of below 1 ns, writing, manipulation and read-out of a qbit requires ultrafast laser pulses interacting coherently with the system. A key experiment in this context is the observation of Rabi oscillations, where the population of a two-level system can be driven coherently back and forth between the ground state and the excited state. An almost shot-noise limited reflection pump-probe technique was employed by which we accomplished to measure Rabi oscillations in one of the fine structure split ground state excitonic states of our QDs, monitoring its population by the bleaching it imposes on the second ground state exciton transition. The first period of these population oscillations yields a dipole moment of about 10 Dy for the s-shell exciton. A second period is still visible, but stretched and shifted to higher pulse areas, which could be due to screening processes caused by carriers that are optically excited in the GaAs substrate.