Our paper on testing non-Gaussian character of Schroedinger’s cat state produced under realistic conditions has been published in Physical Review A [10.1103/PhysRevA.86.043813].
In collaboration with QUIN group of prof. Ulrik Andersen we have experimentally verified the quantum non-Gaussian character of a conditionally generated noisy squeezed single-photon state with a positive Wigner function. Employing an optimized witness based on probabilities of squeezed vacuum and squeezed single-photon states, we have proven that the state cannot be expressed as a mixture of Gaussian states. In our experiment, the non-Gaussian state was generated by conditional subtraction of a single photon from a squeezed vacuum state. The state was probed with a homodyne detector and the witness was determined by averaging a suitable pattern function over the measured homodyne data.
The non-Gaussianity witness was proposed by Radim Filip and Ladislav Mišta Jr. [10.1103/PhysRevLett.106.200401] and then experimentally tested on heralded single-photon source using HBT-like measurement [10.1103/PhysRevLett.107.213602]. The recent paper applies the optimized witness on the homodyne measurement. Further experiments employ solid state single-photon sources such as quantum dots [arXiv:1211.2993].
