The distance in quantum communication is limited for direct transmission, but can be increased by the means
of entanglement swapping implemented in a quantum relay1 or quantum repeater configuration.2 Apart from
this, entanglement swapping is an intriguing phenomenon in quantum physics and deserves thus by itself to be
demonstrated in an experiment. Here we present an entanglement swapping experiment realized for the first
time with autonomous CW-sources.
"Entanglement swapping with high coherence photon pair sources", Proc. SPIE 6780, Quantum Communications Realized, 67800G (10 September 2007); doi: 10.1117/12.735792; https://doi.org/10.1117/12.735792