Angular Schmidt spectrum of entangled photons derivation of an exact formula and experimental characterization for non-collinear phase matching
Dr. Deepika Choudhury, Prof. Mukesh Kumar, Dr. Pushpendra P. Singh, Prof. Rajesh V. Nair, L. Taneja, S. Aarav, A. K. Jha , 
Phys. Rev. A 97, 063846