Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 11: Focus Session: Single Particle Sources for Electronic Devices II
(Joint session of HL and TT organized by HL)
TT 11.7: Vortrag
Montag, 7. März 2016, 17:30–17:45, H10
A charge-driven feedback loop in the resonance fluorescence of a single quantum dot — •Benjamin Merkel1, Annika Kurzmann1, Jan-Hindrik Schulze2, André Strittmatter2, Martin Geller1, and Axel Lorke1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany — 2Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstrasse 36, 10623 Berlin, Germany
Generating photons with transform-limited linewidths from semiconductor quantum dots (QDs) is challenging. Charge and spin noise from the environment cause spectral fluctuations of the resonance, limiting the generation of highly coherent photons.
In our micro-patterned samples we observe an electro-optical feedback mechanism by which the QD resonance frequency follows the excitation, leading to an optical bistability of the fluorescence signal. This feedback loop can be used to stabilize the resonance and reduce the noise of the emitted photons. We investigate the effect on InGaAsGaAs QDs by time-resolved measurements of the fluorescence under two-colour excitation and also in a magnetic field. Experiments show a purely electrical origin of the feedback which lies in the formation of a hole gas at a valence band discontinuity close to the dot. The accumulated positive charge leads to a Stark shift of the dot’s resonance frequencies. The hole gas is fed by carriers that are generated by resonant excitation of excitons in the dot and that tunnel into the hole gas states at the AlGaAs/GaAs interface. We are able to quantitatively reproduce the feedback dynamics by a numerical rate-equation model.