Experimental characterization of multimode photon-subtracted twin beams

States obtained from multimode twin beams by symmetric as well as asymmetric photon subtraction are experimentally investigated. Using the joint photocount distributions measured by an intensified CCD camera, their joint photon-number distributions are reconstructed. Mean photon numbers, Fano factors, and noisereduction parameters are determined for the group of states reached by subtracting up to four photocounts in each beam. Photon subtraction is monitored using the nonclassicality depths and joint quasidistributions of integrated intensities of the emerging states. The non-Gaussianity of the obtained states is also determined. The states reached by coherent photon subtraction are also analyzed. The investigations represent an important step towards the use of photon-subtracted twin beams in sub-shot-noise metrology and imaging.