A scalable photon number resolving detector

A novel photon-number-resolving detector (PNRD) structure, based on an array of nanowire superconducting single photon detectors (SSPDs) connected in series, have recently been proposed. With this configuration, it is possible to scale to large photon numbers. In this framework, PNRDs capable of resolving up to four, eight and twelve photons at telecommunication wavelengths have been fabricated and tested. The photon-induced voltage signals from all the series elements are summed up into a single readout pulse with a height proportional to the detected photon number. Analysis of the linearity shows the potential of scaling to an even larger dynamic range.