A photonic quantum interface for visible-to-telecommunication wavelength conversion

In our recent studies, we demonstrated a conversion of a visible photon at 780 nm to a 1522-nm photon by using difference frequency generation. Intensity correlation measurement on the converted light confirmed that the non-classical property of the input single photon is retained over the conversion process. We further performed a conversion of one half of an entangled photon pair and observed a highly entangled photon pair at 780-nm and 1522-nm, which shows that the quantum information is really transferred in the quantum interface.