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HL: Fachverband Halbleiterphysik
HL 24: Quantum dots: Optics
HL 24.8: Talk
Wednesday, March 29, 2023, 11:45–12:00, POT 151
Preparation of spin qubits in droplet-etched GaAs quantum dots using quasi-resonant excitation — •Caspar Hopfmann1, Nand Lal Sharma1, Weijie Nie1, Robert Keil1, Fei Ding2, and Oliver G. Schmidt1,3,4 — 1Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden — 2Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstr. 2, 30167 Hannover — 3Material Systems for Nanoelectronics, Technische Universität Chemnitz, 09107 Chemnitz — 4Nanophysics, Faculty of Physics and Würzburg-Dresden Cluster of Excellence ct.qmat, TU Dresden, 01062 Dresden
Optically accessible quantum memories are fundamental for implementations of quantum networks as they facilitate the synchronization required for schemes of long-distance quantum information exchange. In order to use GaAs quantum dots, which so far has proven to be bright on-demand sources of entangled photon pairs, deterministic preparation of specific spin states is necessary. We present a comprehensive study on heralded spin preparation employing excited state resonances of droplet etched GaAs quantum dots. By observation of excitation spectra for a range of fundamental excitonic transitions the properties of different quantum dot energy levels, i.e. shells, are revealed. The innovative use of polarization-resolved excitation and detection in the context of quasi-resonant excitation spectroscopy of quantum dots greatly simplifies the determination of the spin preparation fidelities. By employing this method, spin preparation fidelities of quantum dot ground states of up to 85 % are found.