We present a first experimental test of the existence of Spontaneus Parametric Up Conversion, predicted by a specific local realistic model based on Wigner function formalism. The measurement has been made using a ccd camera on the emission of a LiIO3 crystal pumped by a 351 nm and/or a 789 (1064) nm lasers. We obtain an upper limit of 160 times on the ratio between intensity of Spontaneus Parametric Up Conversion and Spontaneous Parametric Down conversion.
@article{arxiv.quant-ph/0307094,
title = {Experimental limit on Spontaneous Parametric Up Conversion},
author = {G. Brida and M. Genovese and M. Gramegna and C. Novero},
journal= {arXiv preprint arXiv:quant-ph/0307094},
year = {2015}
}