Optimizing photon-number resolution with superconducting nanowire multi-photon detectors

In this paper we briefly review the state-of-the-art of intrinsic photon-number resolution (PNR) with superconducting nanowire single-photon detectors (SNSPDs) and will provide an overview of the various experimental techniques employed to achieve PNR. Additionally, we introduce a resolvability criterion to PNR based on SNSPDs.