Quantum Cryptographic Network based on Quantum Memories
  Quantum correlations between two particles show non-classical properties which can be used for providing secure transmission of information. We present a quantum cryptographic system, in which users store particles in quantum memories kept in a transmission center. Correlations between the particles stored by two users are created upon request by projecting their product state onto a fully entangled state. Our system allows for secure communication between any pair of users who have particles in the same center. Unlike other quantum cryptographic systems, it can work without quantum channels and is suitable for building a quantum cryptographic network. We also present a modified system with many centers. 
E. Biham, B Huttner, and T Mor