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The Strathprints institutional repository is a digital archive of University of Strathclyde research outputs. Strathprints provides access to thousands of Open Access research papers by University of Strathclyde researchers, including those from the School of Psychological Sciences & Health - but also papers by researchers based within the Faculties of Science, Engineering, Humanities & Social Sciences, and from the Strathclyde Business School.

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Precise quantum tomography of photon pairs with entangled orbital angular momentum

Jack, B. and Leach, J. and Ritsch, H. and Barnett, S.M. and Padgett, M.J. and Franke-Arnold, S. (2009) Precise quantum tomography of photon pairs with entangled orbital angular momentum. New Journal of Physics, 11. pp. 1-12. ISSN 1367-2630

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We report a high fidelity tomographic reconstruction of the quantum state of photon pairs generated by parametric down-conversion with orbital angular momentum (OAM) entanglement. Our tomography method allows us to estimate an upper and lower bound for the entanglement between the down-converted photons. We investigate the two-dimensional state subspace defined by the OAM states ± and superpositions thereof, with =1, 2, ..., 30. We find that the reconstructed density matrix, even for OAMs up to around =20, is close to that of a maximally entangled Bell state with a fidelity in the range between F=0.979 and F=0.814. This demonstrates that, although the single count-rate diminishes with increasing , entanglement persists in a large dimensional state space.