Quantum information transfer in a wavelength conversion experiment

The experiment performed aims to transfer the quantum information (QI) carried by "telecom photons" at 1310 nm to "visible photons". This is a necessary step to realize a quantum interface between photons and atoms. To this end, in the most general case, entanglement produced by parametric down-conversion is preserved when submitting one photon out of an entangled pair to a wavelength up-conversion process (i.e. sum frequency generation SFG) in a nonlinear crystal.