Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 52: Quantum dots and wires: Optical properties IV

HL 52.4: Vortrag

Freitag, 31. März 2006, 11:45–12:00, POT 151

Optical control of spin coherence in singly charged (In,Ga)As/GaAs quantum dots — •Alex Greilich¹, R. Oulton¹, E.A. Zhukov¹, I.A. Yugova¹, D.R. Yakovlev^1,2, M. Bayer¹, A. Shabaev³, Al.L. Efros³, I.A. Merkulov², V. Stavarache⁴, D. Reuter⁴, and A. Wieck⁴ — ¹Experimentelle Physik II, Universität Dortmund, D-44221, Germany — ²A.F. Ioffe Physico-Technical Institute, RAS, St. Petersburg, 194021, Russia — ³Naval Research Laboratory, Washington, DC 20375, USA — ⁴Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany

Electron spin coherence has been studied in n-type modulation doped (In,Ga)As/GaAs quantum dots (QDs) which contain on average a single electron per dot. The coherence arises from resonant excitation of the QDs by circularly polarized picosecond laser pulses, creating a coherent superposition of an electron and a trion state. Time dependent Faraday rotation is used to probe the spin precession of the optically oriented electrons about a transverse magnetic field. Spin coherence generation can be controlled by the pulse intensity, being most efficient for (2n + 1) π pulses.