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Measurement of the transverse spatial quantum state of light at the single-photon level

Brian J. Smith·Bryan Killett·M. G. Raymer·I. A. Walmsley·K. Banaszek
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Abstract

We present an experimental method to measure the transverse spatial quantum state of an optical field in coordinate space at the single-photon level. The continuous-variable measurements are made with a photon-counting, parity-inverting Sagnac interferometer based on all-reflecting optics. The technique provides a large numerical aperture without distorting the shape of the wave front, does not introduce astigmatism, and allows for characterization of fully or partially coherent optical fields at the single-photon level. Measurements of the transverse spatial Wigner functions for highly attenuated coherent beams are presented and compared to theoretical predictions.

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Brian J. Smith, Bryan Killett, M. G. Raymer, I. A. Walmsley, K. Banaszek. 2005-07-14. Measurement of the transverse spatial quantum state of light at the single-photon level. https://doi.org/10.1364/ol.30.003365

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