Abstract

Recently, photon number resolving detectors, which are based on micro-calorimeters with superconducting transition edge sensors (TESs) [1], have shown excellent performances such as high quantum efficiency of 89 %, and high energy resolution of 0.2 eV [2]. To extend their applications to quantum telecommunication fields, however, the detectors should have high timing properties of the low timing jitters and the fast recovering time. To achieve these properties, we have developed new TES detectors with a titanium-based superconductor. Titanium has the transition temperature (T_c) at 0.39 K in bulk. This will improve the timing properties of TES devices because the operating temperature at T_c is strongly related to the intrinsic time constant of the device and the thermal diffusions of the incident photon energy.

© 2007 IEEE