Photon coincidence counting in parametric down-conversion: Interference of field-matter quantum pathways

摘要

The coincidence rate in two detectors that register signal and idler photons in parametric down-conversion isncalculated using a quantum description of the radiation field that extends the semiclassical theory to the resonancenregime. The signal is given by a sum over paths in the joint field plus matter space, each involving a pair ofnsites (molecules) and six radiation field modes. It may not be factorized into amplitudes representing one-site,nthree-mode paths. All effects of multiple vacuum modes are accounted for by theses paths without adding anLangevin noise source. The molecular information is given by a time-ordered superoperator Green’s functionnrather than the susceptibility χ(2) used in the semiclassical theory.