Deterministic quantum-dot microlenses allow for efficient extraction of indistinguishable, single photons from quantum dots.
M. Gschrey, et al. Highly indistinguishable photons from deterministic quantum-dot microlenses utilizing three-dimensional in situ electron-beam lithography. Nat. Commun. 6, 7662 (2015).
DOI: 10.1038/ncomms8662