Operating quantum waveguide circuits with superconducting single-photon detectors

Advanced quantum information science and technology (QIST) applications place exacting demands on optical components. Quantum waveguide circuits offer a route to scalable QIST on a chip. Superconducting single-photon detectors (SSPDs) provide infrared single-photon sensitivity combined with low dark counts and picosecond timing resolution. In this study, we bring these two technologies together. Using SSPDs we observe a two-photon interference visibility of 92.3 +/- 1.0% in a silica-on-silicon waveguide directional coupler at lambda=804 nm-higher than that measured with silicon detectors (89.9 +/- 0.3%). We further operated controlled-NOT gate and quantum metrology circuits with SSPDs. These demonstrations present a clear path to telecom-wavelength quantum waveguide circuits. (C) 2010 American Institute of Physics. [doi:10.1063/1.3413948]