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New Journal of Physics Quantum Cryptography Focus Issue

July 10, 2002

Real advances in quantum cryptography are described today, 12 July 2002, in a special issue of New Journal of Physics, published jointly by the Institute of Physics and the German Physical Society.

Electronic transfer of information is vulnerable to attack by "eavesdroppers", hence the use of encryption techniques. Underlying nearly all forms of encryption is the necessity for a truly secret key, a random string of zeros and ones. The basic notion of quantum cryptography is to employ single photon transmissions to distribute the random key, while removing the threat of an undetected eavesdropper. Quantum cryptography was first suggested nearly twenty years ago. Papers in this issue of New Journal of Physics show how researchers are coming closer to making it a reality.

A world record for quantum key distribution is described by D Stucki, N Gisin, O Guinnard, G Ribordy and H Zbinden, who have exchanged quantum keys over 67 kilometres of optical fibre. Another record breaking paper, by R J Hughes, J E Nordholt, D Derkacs and C G Peterson, demonstrates quantum key distribution without fibres, sending quantum keys through 10 kilometres of air.

Preventing eavesdropping is discussed in papers by N Lütkenhaus and M Jahma, and by D G Enzer, P G Hadley, R J Hughes, C G Paterson and P G Kwiat, who describe a totally new system using "polarisation-entangled" photons, which provides a means of automatic source verification.

Looking to the future, two papers describe possibilities that could lead to the world`s first quantum network. Jeffrey H Shapiro describes a method to combine a novel source of entangled photons with a way to create "trapped-atom quantum memories", and C Elliott gives a provocative view of how these technologies may be merged into network operation.

Institute of Physics