Direct characterization of a nonlinear photonic circuit's wave function with laser light

Francesco Lenzini, Alexander N. Poddubny, James Titchener, Paul Fisher, Andreas Boes, Sachin Kasture, Ben Haylock, Matteo Villa, Arnan Mitchell, Alexander S. Solntsev, Andrey A. Sukhorukov, Mirko Lobino*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    37 Citations (Scopus)


    Integrated photonics is a leading platform for quantum technologies including nonclassical state generation 1, 2, 3, 4, demonstration of quantum computational complexity 5 and secure quantum communications 6. As photonic circuits grow in complexity, full quantum tomography becomes impractical, and therefore an efficient method for their characterization 7, 8 is essential. Here we propose and demonstrate a fast, reliable method for reconstructing the two-photon state produced by an arbitrary quadratically nonlinear optical circuit. By establishing a rigorous correspondence between the generated quantum state and classical sum-frequency generation measurements from laser light, we overcome the limitations of previous approaches for lossy multi-mode devices 9, 10. We applied this protocol to a multi-channel nonlinear waveguide network and measured a 99.28±0.31% fidelity between classical and quantum characterization. This technique enables fast and precise evaluation of nonlinear quantum photonic networks, a crucial step towards complex, large-scale, device production.

    Original languageEnglish
    Article number17143
    JournalLight: Science and Applications
    Issue number1
    Publication statusPublished - 12 Jan 2018


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