Berlin 2018 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 4: Quantum dots and wires: Optical properties I
HL 4.8: Vortrag
Montag, 12. März 2018, 11:30–11:45, EW 201
High Contrast Differential Reflection Measurements on a Single Quantum Dot — •Pia Eickelmann1, Annika Kurzmann1, Rüdiger Schott2, Andreas D. Wieck2, Arne Ludwig2, Axel Lorke1, and Martin Geller1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg — 2Chair of Applied Solid State Physics, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
Excitons in semiconductor quantum dots (QDs) are promising candidates for the realization of quantum information technologies. Resonance fluorescence is a widely used possibility to address single excitons, where the laser background is suppressed by cross-polarization of two polarizers. Another possibility is differential reflection, where the ratio between the signal of a single QD and the reflected laser light is determined by lock-in technique. However, this technique was limited to low contrasts between QD photons and back-scattered laser light in the order of 10 % [A. N. Vamivakas, et al., Nano Lett. 7, 2892 (2007)].
In this talk we present an optimized sample structure which significantly increases the collection efficiency of the QD photons. A distributed Bragg reflector and an epitaxially grown gate allows us to measure contrasts up to more than 80 %, in confocal rejection even exceeding 800 %. It enables us to perform measurements on a single dot without the modulation of the lock-in technique. These findings open up the possibility to obtain optical measurements on single QDs without the need of suppressing the backscattered laser light.