A multi-party quantum key distribution protocol based on phase shift operation

A multiparty quantum key distribution protocol is proposed in this paper. The distributor uses a phase shift operation to encode the key sequence into some EPR sequences. The participants perform a phase shift operation on the particles from Bell states according to their private keys, and t out of n participants can use the Lagrange interpolation to recover the EPR sequences. Furthermore, two cooperating participants, one from each of the two disjoint groups, can always reconstruct the original key sequence by only a single-photon measurement. Performance analysis shows that the proposed protocol is simpler and more efficient than the existing schemes.