Here we put forward some considerations on how Hong-Ou-Mandel interferometry provides signatures of frequency entanglement in the two-photon state produced by parametric down-conversion. We find that some quantitative information can be inferred in the limit of long-pulse pumping, while the short-pulse limit remains elusive.
Marco Barbieri, Emanuele Roccia, Luca Mancino, Marco Sbroscia, Ilaria Gianani and Fabio Sciarrino
Scientific Reports 7, 7247 (2017)