 Single-photon detector

A photodetector capable of registering an individual absorbed photon as a distinguishable event. The detection record may include a click time and an output-channel label. Such a detector need not resolve the number of photons in a pulse: an ordinary single-pixel single-photon avalanche diode produces essentially the same saturated avalanche pulse when one or several photons trigger the same detection interval. Detector efficiency, dark counts and detector dead time affect the observed photon counting statistics.