A collaboration between BAQIS (Beijing) and IFIMAC-UAM, published in Optica, reports a Bell inequality violation using single photons from a resonantly driven quantum dot. The quantum dot emits superpositions of vacuum and one photon. Splitting these between two remote nodes and measuring them with Franson interferometers produces time-bin entanglement, with a CHSH parameter of S = 2.675 ± 0.050. That is more than 13 standard deviations above the classical limit. The approach avoids photon-pair sources and offers a bright, simple route to solid-state entangled-photon sources for quantum networks. [Full Article]
