Quantum key distribution network with wavelength addressing
  Most traditional applications of quantum cryptography are point-to-point communications, in which only two users can exchange keys. In this letter, we present a network scheme that enable quantum key distribution between multi-user with wavelength addressing. Considering the current state of wavelength division multiplexing technique, dozens or hundreds of users can be connected to such a network and directly exchange keys with each other. With the scheme, a 4-user demonstration network was built up and key exchanges were performed. 
Xiao-Fan Mo, Tao Zhang, Fang-Xing Xu, Zheng-Fu Han, and Guang-Can Guo