Constrained MaxLik reconstruction of multimode photon distributions
  We address the reconstruction of the full photon distribution of multimode fields generated by seeded parametric down-conversion (PDC). Our scheme is based on on/off avalanche photodetection assisted by maximum-likelihood (MaxLik) estimation and does not involve photon counting. We present a novel constrained MaxLik method that incorporates the request of finite energy to improve the rate of convergence and, in turn, the overall accuracy of the reconstruction. 
G. Brida, M. Genovese, A. Meda, S. Olivares, M. G. A. Paris, F.   Piacentini