Spatial separation of collinearly emitted broadband frequency-correlated photon pairs

We experimentally study the separation of broadband photon pairs that share the same properties in all degrees of freedom. We find that broadband photon pairs with a bandwidth of about 90 nm can be efficiently separated using time-reversed Hong-Ou-Mandel (HOM) interference. The frequency correlation of the separated photons is verified through joint spectral intensity measurements. The visibility of the HOM interference between the separated photons is shown to be higher than the classical limit of 50%, ensuring that the separated photons are indistinguishable. These results may contribute to improving the performance of quantum sensing and quantum communication.