Quantum Privacy Amplification and the Security of Quantum Cryptography over Noisy Channels

David Deutsch, Artur Ekert, Richard Jozsa, Chiara Macchiavello, Sandu Popescu, Anna Sanpera
1996 Physical Review Letters  
Existing quantum cryptographic schemes are not, as they stand, operable in the presence of noise on the quantum communication channel. Although they become operable if they are supplemented by classical privacy-amplification techniques, the resulting schemes are difficult to analyse and have not been proved secure. We introduce the concept of quantum privacy amplification and a cryptographic scheme incorporating it which is provably secure over a noisy channel. The scheme uses an 'entanglement
more » ... urification' procedure which, because it requires only a few quantum Controlled-Not and single-qubit operations, could be implemented using technology that is currently being developed. The scheme allows an arbitrarily small bound to be placed on the information that any eavesdropper may extract from the encrypted message.
doi:10.1103/physrevlett.77.2818 pmid:10062053 fatcat:nurggnojbrgzfnmsg5hmecqgee