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Quantum leap for secure comms?

By Leon Engelbrecht, ITWeb senior writer
Johannesburg, 07 Jul 2008

The Council for Scientific and Industrial Research (CSIR) and the University of KwaZulu-Natal are studying ways to exploit quantum physics to better secure information transfer.

The CSIR's latest newsletter reports that National Laser Centre researchers Angela Dudley and Melanie McLaren, led by Andrew Forbes, and academics from the University of KwaZulu-Natal have started an ambitious project to investigate quantum entanglement using vortex beams in the telecommunications and secure data transfer fields.

Quantum physics deals with atomic and subatomic systems and became a distinct field of study after the discovery that waves have discrete energy packets (called quanta) that behave in a manner similar to particles.

Dudley says an optical vortex is a beam of light of which the phase varies in a corkscrew-like manner along the beam's direction of propagation. On a flat surface, an optical vortex looks like a doughnut - a ring of light with a dark hole in the centre.

"Quantum entanglement is a vital resource in quantum information technology such as quantum computation and quantum cryptography," she says. "The idea is simply to entangle quantum states for secure information transfer, so that the cryptography is based on quantum physics and not man-made codes, which can be broken."

Quantum cryptography makes use of quantum entanglement in the transmitting of information (a key) in quantum states. This communication system is able to detect "eavesdropping"; it involves two communicating users who share information that can be used as a key to encrypt and decrypt messages. Quantum cryptography is used only in producing and distributing the key.

The challenge, says Dudley, is quantum noise and quantum decoherence that occur in optical fibres, resulting in the entanglement gradually being destroyed. This, the team says, it hopes to address.

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