Single-Photon and Photon-Number-Resolving Detectors

Several important advances were reported in single-photon detectors and photon-number-resolving detectors in 2011. New materials with smaller superconducting gaps were demonstrated for superconducting nanowire single-photon detectors (SNSPDs) that led to improved signal-to-noise ratios and infrared performance. Faster superconducting transition edge sensors (TESs) were demonstrated by using normal metal heat sinks. Both TESs and SNSPDs were evanescently coupled with waveguides as a step toward demonstrating quantum photonic integrated circuits. Photon-number resolution has been the goal in several demonstrations using semiconductor detectors, and recent results suggest a potential convergence of Geiger-mode and linear-mode avalanche diodes in exhibiting the high-gain, low-noise analog behavior necessary to reach this goal. There has also been progress focused on additional trends in single-photon avalanche diodes (SPADs) for high- rate counting and detector array scaling.