High-fidelity operation of quantum photonic circuits
Anthony Laing, Alberto Peruzzo, Alberto Politi, Maria Rodas Verde, M. Halder, Timothy C. Ralph, Mark G. Thompson, Jeremy L. O’Brien · Applied Physics Letters · 2010
We demonstrate photonic quantum circuits that operate at the stringent levels that will be required for future quantum information science and technology. These circuits are fabricated from silica-on-silicon waveguides forming directional couplers and interferometers. While our focus is on the operation of quantum circuits, to test this operation required construction of a photon source that produced near-identical pairs of photons. We show nonclassical interference with two photons and a two-photon entangling logic gate that operate with near-unit fidelity. These results are a significant step toward large-scale operation of photonic quantum circuits.