Advanced quantum information science and technology (QIST) applications place exacting de- mands 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\pm1.0% in a silica-on-silicon waveguide directional coupler at \lamda = 804 nm-higher than that measured with silicon detectors (89.9\pm0.3%). We further operated controlled-NOT gate and quantum metrology circuits with SSPDs. These demonstrations present a clear path to telecom-wavelength quantum waveguide circuits.
@article{arxiv.1003.4654,
title = {Operating quantum waveguide circuits with superconducting single-photon detectors},
author = {C. M. Natarajan and A. Peruzzo and S. Miki and M. Sasaki and Z. Wang and B. Baek and S. Nam and R. H. Hadfield and J. L. O'Brien},
journal= {arXiv preprint arXiv:1003.4654},
year = {2015}
}