QUANTUM CRYPTOGRAPHIC NETWORK-BASED ON QUANTUM MEMORIES

Quantum correlations between two particles show nonclassical propertie s that can be used for providing secure transmission of information. W e present a quantum cryptographic systemin which users store particles in a transmission center, where their quantum states are preserved us ing quantum memories. 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 b etween any pair of users who have particles in the same center. Unlike other quantum cryptographic systems, it can work without quantum chan nels and it is suitable for building a quantum cryptographic network. We also present a modified system with many centers.