Entanglement swapping in a Franson interferometer setup

We propose a simple scheme to swap the non-local correlations, characteristic of a Franson interferometric setup, between pairs of frequency entangled photons emitted by distinct nonlinear crystals in a parametric downconversion process. Our scheme consists of two distinct sources of frequency entangled photons. One photon of each pair is sent to a separate Mach-Zehnder interferometer while the other photons of the pairs are mixed by a beam splitter and then detected in an Ou-Mandel interferometer. For suitably postselected joint measurements, the photons sent at the Mach-Zehnder show a coincidence photocount statistics which depends non-locally on the settings of the two interferometers.