Parametric down-conversion photon-pair source on a nanophotonic chip

• Published in: Light, science & applications Vol. 6; no. 5; p. e16249
• Main Authors: Guo, Xiang, Zou, Chang-ling, Schuck, Carsten, Jung, Hojoong, Cheng, Risheng, Tang, Hong X
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.05.2017; Springer Nature B.V; Nature Publishing Group
• Subjects: 142/126; 639/624/1075/1079; 639/624/399/1097; 639/624/400/385; 639/766/1130/2799; Aluminum; Applied and Technical Physics; Atomic; Chips; Classical and Continuum Physics; Detectors; Information processing; Integrated circuits; Lasers; Light; Light sources; Molecular; Nanostructure; Nonlinear systems; Nonlinearity; Optical and Plasma Physics; Optical Devices; Optics; Original; original-article; Photonics; Photons; Physics; Physics and Astronomy; Quantum theory; Scaling; Semiconductors; second-order nonlinear material; quantum photonic chip; single-photon source; nanofabrication
• ISSN: 2047-7538; 2095-5545; 2047-7538
• DOI: 10.1038/lsa.2016.249

Quantum-photonic chips, which integrate quantum light sources alongside active and passive optical elements, as well as single-photon detectors, show great potential for photonic quantum information processing and quantum technology. Mature semiconductor nanofabrication processes allow for scaling such photonic integrated circuits to on-chip networks of increasing complexity. Second-order nonlinear materials are the method of choice for generating photonic quantum states in the overwhelming majority of linear optic experiments using bulk components, but integration with waveguide circuitry on a nanophotonic chip proved to be challenging. Here, we demonstrate such an on-chip parametric down-conversion source of photon pairs based on second-order nonlinearity in an aluminum-nitride microring resonator. We show the potential of our source for quantum information processing by measuring the high visibility anti-bunching of heralded single photons with nearly ideal state purity. Our down-conversion source yields measured coincidence rates of 80 Hz, which implies MHz generation rates of correlated photon pairs. Low noise performance is demonstrated by measuring high coincidence-to-accidental ratios. The generated photon pairs are spectrally far separated from the pump field, providing great potential for realizing sufficient on-chip filtering and monolithic integration of quantum light sources, waveguide circuits and single-photon detectors. Quantum optics: photon-pair source on a chip A chip-based source of photon pairs for applications in quantum information processing has been built by a team of scientists in the US. Xiang Guo and co-workers from Yale University built the quantum light source from an aluminum nitride microring resonator. The strong second-order nonlinearity of the aluminum nitride yields efficient parametric down-conversion. This allows 775-nm-wavelength pump photons to be converted into a pair of entangled photons in the telecommunications window of 1550 nm. Tests indicated that the heralded photons generated by the microring source are anti-bunched and have high visibility and a high purity of state, indicating that they are highly suitable for use in quantum optics experiments. In principle, the on-chip source is compatible with megahertz generation rates and large-scale manufacture of integrated optical circuits.