Power-efficient production of photon pairs in a tapered chalcogenide microwire

Using tapered fibers of As2Se3 chalcogenide glass, we produce photon pairs at telecommunication wavelengths with low pump powers. We found maximum coincidences-to-accidentals ratios of $2.13\pm0.07$ for degenerate pumping with 3.2 {\mu}W average power, and $1.33\pm0.03$ for non-degenerate pumping with 1.0 {\mu}W and 1.5 {\mu}W average power of the two pumps. Our results show that the ultrahigh nonlinearity in these microwires could allow single-photon pumping to produce photon pairs, enabling the production of large entangled states, heralding of single photons after lossy transmission, and photonic quantum information processing with nonlinear optics.