Operating quantum waveguide circuits with superconducting single-photon detectors
C. M. Natarajan, Alberto Peruzzo, S. Miki, M. Sasaki, Z. Wang, B. Baek, S. Nam, Robert H. Hadfield, J. L. O’Brien · Applied Physics Letters · 2010
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 λ=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.