Hannover 2010 – scientific programme

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MO: Fachverband Molekülphysik

MO 24: Poster: Quantum Control

MO 24.5: Poster

Thursday, March 11, 2010, 16:00–18:30, Lichthof

Coherent Control of multiphoton-processes in colloidal semiconductor nanocrystals — •Martin Ruge, Matthias Wollenhaupt, Thomas Baumert, and Alexander Horn — Universität Kassel, Institut für Physik und Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), Heinrich-Plett-Str. 40, D-34132 Kassel, Germany

In the recent past semiconductor nanocrystals - further referred as quantum dots (QDs) - have gained interest due to their atomic-like energy level structure. Coherent control of quantum states in single QDs has been demonstrated by double pulses [1]. So far, experiments were performed on epitactically grown QDs either sandwiched between semiconductor materials or grown on the surface of the latter and therefore the resonance energies are restricted to the infrared spectral range [1,2]. Here we present coherent control of multiphoton induced photoluminescence (mpl) of colloidal semiconductor quantum dots with one photon resonance energies in the visible spectral range by phase-modulated femtosecond laser radiation. The beam is focused in a dispersion of QDs and the luminescence is investigtated in dependence on the applied phase modulation functions and parameters. Part of the signals can be explained in terms of higher order spectral interference other parts rely on further control mechanisms. The results obtained within the scope of this experiments could lead to new applications e.g. color generation in QD doped materials like glasses.

[1] N. H. Bonadeo et al., Science 282 (1998) 20

[2] S. Stufler, Phys. Rev. B 73 (2006) 125304