Regensburg 2022 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 2: Spin Phenomena in Semiconductors
HL 2.3: Talk
Monday, September 5, 2022, 10:15–10:30, H31
Selective optical charging and spin preparation of a single quantum dot molecule — •C. Thalacker1, F. Bopp1, A. Ahmadi1, N. Revenga1, F. Vögl1, C. Cullip1, K. Boos1, F. Sbresny1, N. Bart2, A. Wieck2, A. Ludwig2, D. Reuter3, J. Schall4, S. Reitzenstein4, H. Riedl1, K. Müller1, and J. J. Finley1 — 1Walter Schottky Institut and Physik Department, TU München, Garching, Germany — 2Ruhr-Universität Bochum, Bochum, Germany — 3Universität Paderborn, Paderborn, Germany — 4Technische Universität Berlin, Berlin, Germany
Coherence, ease of control and scalability lie at the heart of hardware for distributed quantum technologies. Spin-photon interfaces based on III-V semiconductor quantum dots (QDs) combine properties such as strong light-matter-interactions, robust spin-photon selection rules and ease of integration into opto-electronic devices. Two vertically stacked QDs, a so-called QD-molecule (QDM) are expected to exhibit enhanced coherence times (T2*) due to the formation of singlet-triplet (S-T) qubits. We embed a single QDM into an ultralow capacitance p-i-n diode that allows for ultrafast electrical tuning (>500 MHz). Photon extraction efficiencies are improved to >20% by deterministically placing a circular Bragg grating around the QDM. Using our device we demonstrate all optical control of the charge state, as well as optical spin pumping. Our results form the basis of an optically active S-T spin-qubit with enhanced coherence.