Tripartite quantum correlations obtained by post-selection from twin beams

Spatially-resolved photon counting of a twin beam performed by an iCCD camera allows for versatile tailoring of the properties of the beams formed by parts of the original twin beam. Dividing the idler beam of the twin beam into three equally intense parts and post-selecting by detecting a given number of photocounts in the whole signal beam we arrive at the idler fields exhibiting high degrees of nonclassicality and being endowed with tripartite quantum correlations. Nonclassicality is analyzed with the help of suitable nonclassicality witnesses and their corresponding nonclassicality depths. Suitable parameters are introduced to quantify quantum correlations. These parameters are analyzed as they depend on the field intensity. The experimental photocount histograms are reconstructed by the maximum-likelihood approach and the obtained photon-number distributions are compared with a suitable model in which the original twin beam is approximated by an appropriate multi-mode Gaussian field and undergoes the corresponding beams’ transformations.