Low-temperature optical photon detectors for quantum information applications

There is increasing interest in using high-performance cryogenic optical photon detectors in a variety of applications in quantum information science and technology. These applications require detectors that have extremely low dark count rates, high count rates, high quantum efficiency, and moderate energy resolution for IR to optical photons. We describe three applications, quantum key distribution, quantum optics with spontaneous parametric down converters, and linear optical quantum computing. We also describe preliminary results using a superconducting tungsten transition-edge sensor in a quantum key distribution system and a quantum optics experiment with spontaneous parametric down converters.