Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 60: Focus Session: Coherent dynamics in semiconductor nanostructures and coupled devices

HL 60.3: Topical Talk

Wednesday, March 13, 2013, 16:00–16:30, H16

Ultrafast coherent exciton dynamics in individual quantum dots - phonons, coherent coupling, and CQED — •Wolfgang Langbein — School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA, United Kingdom

Excitons are the fundamental optical excitations of semiconductors, determining their optoelectronic properties important for present devices such as light emitting diodes and semiconductor lasers. The coherent dynamics of the excitonic excitation is dominated by coupling to phonons and photons. The three-dimensional confinement in quantum dots (QDs) creates a finite excitation volume, yielding a discrete excitonic spectrum and phonon-assisted transitions which are enhanced with decreasing volume. The zero-phonon transition dynamics can be dominated by radiative coupling at low temperatures [10.1103/PhysRevB.70.033301], and inserting the QDs into an optical cavity the quantum strong coupling regime of CQED can be reached [10.1038/NMAT2717]. Spatially separated excitons can be coupled via an optical cavity [arXiv1206.0592], or for weakly confined excitons via a two-dimensional continuum [10.1038/NPHOTON.2010.284]. I will present measurements on QD ensembles and individual QDs using nonlinear optical spectroscopy[10.1393/ncr/i2010-10054-1], including using heterodyne detected photon echo and two-dimensional spectroscopy using heterodyne spectral interferometry [10.1364/OL.31.001151].