Abstract

Photon counters with high efficiency, high time resolution, low dark counts and high photon detection-rates are indispensable elements of optical circuits. Superconducting nanowire single-photon detectors (SNSPDs) have been proven as one of the most promising photonic technology to meet performance requirements of quantum optical measurements. I will explain the operation of NbTiN supercondcuting photon detectors fabricated in two implementations: (1) detectors coupled to optical fibers and (2) integrated detectors coupled to dielectric waveguides. Detection efficiency higher than 90% in the infrared range, 100 MHz photon detection-rate, dark counts of mHz and timing jitter below 15 ps are shown. The operation of the detector is based on the transition of a nanowire from the superconductive to the resistive state upon the absorption of at least a single photon. The devices are operated in a closed-cycle cryostat at 2.5 Kelvin. This turn-key approach enables continuous operation for up to 10,000 hours and requires no liquid helium consumption, providing plug and optical measurements. SNSP Ds have found important applications in (quantum) optical communication, information technology, time-resolved spectroscopy, laser ranging and remote sensing (LiDAR). SNSPD are envisioned as crucial photon detectors for the development of all new technologies where photon counting, high sensitivity, fast time response and low noise are required.