PT Unknown AU Marsili, F Bitauld, D Divochiy, A Gaggero, A Leoni, R Mattioli, F Korneev, A Seleznev, V Kaurova, N Minaeva, O Gol’tsman, G Lagoudakis, KG Benkahoul, M Lévy, F Fiore, A TI Superconducting nanowire photon number resolving detector at telecom wavelength SE CLEO/QELS PY 2008 BP Qmj1 (1 to 2) DE PNR SSPD; SNSPD; Detectors; Infrared; Low light level; Diode lasers; Photons; Scanning electron microscopy; Superconductors; Ti:sapphire lasers AB We demonstrate a photon-number-resolving (PNR) detector, based on parallel superconducting nanowires, capable of resolving up to 5 photons in the telecommunication wavelength range, with sensitivity and speed far exceeding existing approaches. ER