Practical quantum cryptography based on two-photon interferometry
ARTUR K. EKERT, John Rarity, Paul R. Tapster, G. Massimo Palma · Physical Review Letters · 1992
We propose an experimental realization of cryptographic-key-sharing scheme exploiting quantum correlations between pair photons. Our experimental setup consists of an external source of correlated photon pairs which propagate to two widely separated unbalanced Mach-Zehnder interferometers. The probability of detection of photon pairs in any two outputs of the interferometers can be fully modulated by phase plates in either interferometer.