Publications associated with Optical Quantum Technologies

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

Optics Letters 30 (2005) 3365-3367

BJ Smith, B Killett, MG Raymer, IA Walmsley, K Banaszek

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 photoncounting, parity-inverting Sagnac interferometer based on all-reflecting optics. The technique provides a large numerical aperture without distorting the shape of the wavefront, 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 with theoretical predictions. © 2005 Optical Society of America.

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