A highly efficient single-photon source based on a quantum dot in a photonic nanowire

The development of efficient solid-state sources of single photons is a major challenge in the context of quantum communication, optical quantum information processing and metrology(1). Such a source must enable the implementation of a stable, single-photon emitter, like a colour centre in diamond(2-4) or a semiconductor quantum dot(5-7). Achieving a high extraction efficiency has long been recognized as a major issue, and both classical solutions(8) and cavity quantum electrodynamics effects have been applied(1,9-12). We adopt a different approach, based on an InAs quantum dot embedded in a GaAs photonic nanowire with carefully tailored ends(13). Under optical pumping, we demonstrate a record source efficiency of 0.72, combined with pure single-photon emission. This non-resonant approach also provides broadband spontaneous emission control, thus offering appealing novel opportunities for the development of single-photon sources based on spectrally broad emitters, wavelength-tunable sources or efficient sources of entangled photon pairs.