Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 9: Quantum dots: Optical properties
HL 9.3: Vortrag
Montag, 16. März 2015, 10:30–10:45, EW 203
Dissipative preparation of the exciton and biexciton in a single self-assembled quantum dot — •Lukas Hanschke1, Manuel Koller1, Per-Lennart Ardelt1, Kevin A. Fischer2, Kai Müller2, Alexander Kleinkauf1, Alexander Bechtold1, Tobias Simmet1, Jakob Wierzbowski1, Gerhard Abstreiter1, and Jonathan J. Finley1 — 1Walter Schottky Institut and Physik-Department, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany — 2E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA
Pulsed resonant fluorescence is used to probe ultrafast phonon-assisted exciton and biexciton preparation in individual self-assembled InGaAs quantum dots. By driving the system using large area (>10π) near resonant optical pulses, we experimentally demonstrate how phonon mediated dissipation within the manifold of dressed excitonic states can be used to prepare the neutral exciton with a fidelity 70%. By comparing the phonon-assisted preparation with resonant Rabi oscillations we show that the phonon-mediated process provides the higher fidelity preparation for large pulse areas and is less sensitive to pulse area variations. By detuning the laser with respect to the exciton transition we map out the spectral density for exciton coupling to the bulk LA-phonon continuum. Similar phonon mediated processes are shown to facilitate direct biexciton preparation via two photon biexciton absorption, with fidelities > 80%. Our results are found to be in very good quantitative agreement with simulations that model the quantum dot-phonon bath interactions with Bloch-Redfield theory.