Photon localisation in parametric down-conversion
Edward R. Pike, Sarben Sarkar · Quantum Optics Journal of the European Optical Society Part B · 1989
A full multimode theory for parametric down-conversion is used to calculate the two-photon detection amplitude. From this amplitude a heuristic argument is given for the configuration space extent of the single photons that are involved. These single phonons have a configuration space localisation consistent with an asymptotic fall off with distance r or r -5/4 in the radial direction.