  Quantum key distribution (QKD) is a crucial technology for information
security in the future. Developing simple and efficient ways to establish QKD
among multiple users are important to extend the applications of QKD in
communication networks. Herein, we proposed a scheme of symmetric dispersive
optics QKD (DO-QKD) and demonstrated an entanglement-based quantum network
based on it. In the experiment, a broadband entanglement photon pair source was
shared by end users via wavelength and space division multiplexing. The wide
spectrum of generated entangled photon pairs was divided into 16 combinations
of frequency-conjugate channels. Photon pairs in each channel combination
supported a fully-connected subnet with 8 users by a passive beam splitter.
Eventually, it showed that an entanglement-based QKD network over 100 users
could be supported by one entangled photon pair source in this architecture. It
has great potential on applications of local quantum networks with large user
number.
