Photon-number discrimination without a photon counter and its application to reconstructing non-Gaussian states
Helen M. Chrzanowski, J. Bernu, Ben M. Sparkes, B. Hage, Austin P. Lund, Timothy C. Ralph, Ping Koy Lam, Thomas Symul · Physical Review A · 2011
The nonlinearity of a conditional photon-counting measurement can be used to ``de-Gaussify'' a Gaussian state of light. Here we present and experimentally demonstrate a technique for photon-number resolution using only homodyne detection. We then apply this technique to inform a conditional measurement, unambiguously reconstructing the statistics of the non-Gaussian one- and two-photon-subtracted squeezed vacuum states. Although our photon-number measurement relies on ensemble averages and cannot be used to prepare non-Gaussian states of light, its high efficiency, photon-number-resolving capabilities, and compatibility with the telecommunications band make it suitable for quantum-information tasks relying on the outcomes of mean values.