Experimental demonstration of 4 party quantum secret sharing and multiparty quantum key distribution

A polarization entangled 4-photon state is shown to be directly created by parametric down-conversion. How this state can be used for quantum secret sharing is discussed. Quantum key distribution is distributed to 3 of the 4 parties. Experimental implementation of this multiparty quantum secure communication schemes and demonstration of a 4-party quantum secret-sharing protocol are presented.