Low noise superconducting single photon detectors on silicon

We have fabricated superconducting nanowire single photon detectors made of NbTiN on a silicon substrate. This type of material reduces the dark count rate by a factor of 10 compared to identical NbN detectors, enabling single photon detection with unprecedented signal to noise ratio: we report a noise equivalent power of 10(-19) W Hz(-1/2) at 4.2 K. The compatibility of our superconducting device with silicon enables its integration with complex structures. (C) 2008 American Institute of Physics.