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Development of site-controlled quantum dot arrays acting as scalable sources of indistinguishable photons

Große, Jan; Helversen, Martin von; Koulas-Simos, Aris; Hermann, Martin; Reitzenstein, Stephan

AG Optoelektronik und Quantenbauelemente

We report on the realization of an array of 28 × 28 mesas with site-controlled InGaAs quantum dots acting as single-photon sources for potential applications in photonic quantum technology. The site-selective growth of quantum dots is achieved by using the buried stressor approach where an oxide aperture serves as the nucleation site in the center of each mesa. Spectroscopic maps demonstrate the positioning of quantum dots with an inhomogeneous broadening of the ensemble emission of only 15.8 meV. Individual quantum dots are characterized by clean single-quantum-dot spectra with narrow exciton, biexciton, and trion lines, with a best value of 27 μeV and an ensemble average of 120 μeV. Beyond that, Hanbury Brown and Twiss and Hong-Ou-Mandel measurements validate the quantum nature of emission in terms of high single-photon purity and photon indistinguishability with a g(2)(0) value of (0.026 ± 0.026) and a post-selected two-photon interference visibility V = (87.1 ± 9.7)% with an associated coherence time of τc = (194 ± 7) ps.