Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 37: Quantum Dots and Wires: Optical Properties I (mainly InGaAs Dots)

HL 37.4: Vortrag

Dienstag, 27. März 2012, 11:30–11:45, ER 164

All optical preparation, storage and readout of a single spin in an individual quantum dot — Vase Jovanov, Florian Klotz, Alexander Bechtold, Stephan Kapfinger, Silvia Spiga, •Sebastian Koch, Daniel Rudolph, Max Bichler, Martin S. Brandt, and Jonathan J. Finley — Walter Schottky Institute and Center for Nanotechnology and Nanomaterials, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany

We demonstrate all optical preparation and storage of a single electron in an individual self-assembled InGaAs quantum dot (QD) and high fidelity measurement of its spin projection by driving a luminescence recycling transition. Hereby, we optically induce spin-charge conversion to convert the spin information into charge occupancy (1e or 2e) and then repeatedly measure the charge occupancy by pumping an excited state of the negatively charged trion. By probing the temperature and magnetic field dependence of the spin dynamics we extract electron and hole Landé g-factors and map out the spectrum and spin structure of hot trion transitions. The devices investigated are QD spin memory structures that can be switched between two modes of operation; (i) charging, where optically generated holes are removed from the dot whilst electrons remain stored due to the presence of an AlGaAs barrier and (ii) readout, where excitons optically pumped into the dot recombine to produce luminescence. The spin lifetime of the stored electron was measured by monitoring the storage time dependence of the spin blockade as the temperature and magnetic field was varied.