Detection of infrared photons with a superconductor

A superconductor single photon detector based on NbN nanowire was fabricated using electron beam lithography (EBL) and reactive ion etching (RIE) for infrared photon detection. When biased well below its critical current at 4.2 K, NbN nanowire is very sensitive to the incident photons. Typical telecommunication photons with a wavelength of 1550 nm were detected by this detector. Data analysis indicates the repeating rate of the device with 200 nm NbN nanowire may be up to 100 MHz, and the quantum efficiency is about 0.01% when biased at 0.95/_c. Supported by the National Basic Research Program of China (Grant Nos 2006CB601006 and 2007CB310404), National High-tech R&D Program of China (Grant No. 2006AA12Z120) and National Natural Science Foundation of China (Grant No. 60721063)