Multiuser-to-multiuser entanglement distribution based on 1550 nm polarization-entangled photons

Telecom-band polarization-entangled photon-pair source has been widely used in quantum communication due to its acceptable transmission loss. It is also used in cooperation with wavelength-division multiplexing (WDM) to construct entanglement distributor. However, previous schemes generally are not suitable for multinode scenario. In this paper, we construct a telecom-band polarization-entangled photon-pair source, and it shows ultrahigh fidelity and concurrence which are both greater than 90% (raw data). Moreover, we set up a four-by-four entanglement distributor based on WDM. We check the 16 Clauser-Horne-Shimony-Holt inequalities, which show nonlocality. Lastly, as an example of practical application of this source, we estimate the quantum bit error rates and quantum secret key rates when it is used in quantum key distribution. Furthermore, the transmission of entanglement in long optical fibers is also demonstrated.