The light produced by parametric down-conversion shows strong spatial entanglement that leads to violations of EPR criteria for separability. Historically, such studies have been performed by scanning a single-element, single-photon detector across a detection plane. Here we show that modern electron-multiplying charge-coupled device cameras can measure correlations in both position and momentum across a multi-pixel field of view. This capability allows us to observe entanglement of around 2,500 spatial states and demonstrate Einstein–Podolsky–Rosen type correlations by more than two orders of magnitude. More generally, our work shows that cameras can lead to important new capabilities in quantum optics and quantum information science.
Edgar, M. P., Tasca, D. S., Izdebski, F., Warburton, R., Leach, J., Agnew, M., Buller, G. S., Boyd, R. W., & Padgett, M. J. (2012). Imaging high-dimensional spatial entanglement with a camera. Nature Communications, 3(n/a), . https://doi.org/10.1038/ncomms1988