Qubit entanglement between ring-resonator photon-pair sources on a silicon chip

Silverstone, J. W. and Santagati, R. and Bonneau, D. and Strain, M. J. and Sorel, M. and O'Brien, J. L. and Thompson, M. G. (2015) Qubit entanglement between ring-resonator photon-pair sources on a silicon chip. Nature Communications, 6. 7948. ISSN 2041-1723

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    Abstract

    Entanglement - one of the most delicate phenomena in nature - is an essential resource for quantum information applications. Scalable photonic quantum devices must generate and control qubit entanglement on-chip, where quantum information is naturally encoded in photon path. Here we report a silicon photonic chip that uses resonant-enhanced photon-pair sources, spectral demultiplexers and reconfigurable optics to generate a path-entangled two-qubit state and analyse its entanglement. We show that ring-resonator-based spontaneous four-wave mixing photon-pair sources can be made highly indistinguishable and that their spectral correlations are small. We use on-chip frequency demultiplexers and reconfigurable optics to perform both quantum state tomography and the strict Bell-CHSH test, both of which confirm a high level of on-chip entanglement. This work demonstrates the integration of high-performance components that will be essential for building quantum devices and systems to harness photonic entanglement on the large scale.