Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 39: Quantum dots: Optical and transport properties

HL 39.5: Talk

Thursday, March 26, 2009, 10:45–11:00, BEY 81

Single mode synchronized precession of electron spins in a quantum dot ensemble — •Stefan Spatzek¹, Alex Greilich¹, Irina Yogova², Ilya A. Akimov¹, Dmitri R. Yakovlev¹, Alexander. L. Efros³, Dirk Reuter⁴, Andreas D. Wieck⁴, and Manfred Bayer¹ — ¹Experimentelle Physik II, Technische Universität Dortmund, 44221 Dortmund, Germany — ²Institute of Physics, St. Petersburg State University, 198504 St. Petersburg, Russia — ³Naval Research Laboratory, 20375 Washington DC, USA — ⁴Angewandte Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany

Optically controlled electron spins in ensembles of quantum dots (QDs) provide an attractive proposal to implement quantum information technologies in a solid-state environment. However inhomogeneities within an ensemble lead to the rapid loss of coherence among the phase of the spins. Electron spin coherence in an inhomogeneous, singly charged (InGa)As/GaAs ensemble of dots was studied by means of time-resolved Faraday-Rotation technique [1].

The spin of all electrons confined in the dots can be driven into a single precession mode about a magnetic field. This precession regime is reached by allowing only a single mode within the electron spin precession spectrum of the QD ensemble to be synchronized with the excitation train of optical pulses. Under this condition a nuclear induced frequency focusing effect [2] leads to a shift of all spin precession frequencies to the synchronized mode. [1] A. Greilich et al., Science 313, 341 (2006) [2] A. Greilich et al., Science 317, 1896 (2007)