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arXiv · 1703.01007

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
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Abstract

Integrated photonics is a leading platform for quantum technologies including nonclassical state generation \cite{Vergyris:2016-35975:SRP, Solntsev:2014-31007:PRX, Silverstone:2014-104:NPHOT, Solntsev:2016:RPH}, demonstration of quantum computational complexity \cite{Lamitral_NJP2016} and secure quantum communications \cite{Zhang:2014-130501:PRL}. As photonic circuits grow in complexity, full quantum tomography becomes impractical, and therefore an efficient method for their characterization \cite{Lobino:2008-563:SCI, Rahimi-Keshari:2011-13006:NJP} 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 multimode devices \cite{Liscidini:2013-193602:PRL, Helt:2015-1460:OL}. We applied this protocol to a multi-channel nonlinear waveguide network, and measured a 99.28$\pm$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.

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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. 2017-03-03. Direct characterization of a nonlinear photonic circuit's wave function with laser light. https://doi.org/10.1038/lsa.2017.143

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