BBC News | SCI/TECH | Paving the way for 'uncrackable' codes
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1709000/1709322.stm
Summary:
- The heart of a new light-emitting diode (LED) developed in Cambridge, UK,
can be controlled so precisely that it emits just one single photon of
light each time it is switched on.
- The device could be a key component in quantum cryptography, a
code-making technology which, it is hoped, will be uncrackable.
- The laws of quantum mechanics dictate that it provides a way to guarantee
that no-one has intercepted that key," Andrew Shields of Toshiba Research
Europe Limited (TREL) told BBC News Online.
- Dr Shields and colleagues from TREL and the University of Cambridge built
the single photon-emitting diode using standard semiconductor manufacturing
techniques.
- The reason security experts are interested in using single photons to
carry encoded messages is that they appear to provide the guarantee of
secrecy that other technologies lack.
- The kind of encoding currently used to protect messages relies on the
fact that, without the key, it would take an extremely long time to do all
the calculations needed to unscramble a secret message.
- With quantum cryptography, the very act of intercepting a single photon
on its way down an optical fibre would change the information it was carrying.
- "We need the detection technology for single photons," said Dr Shields.
- Previous emitters have occasionally let out more than one identical
photon at a time, a problem that could have opened the door to an eavesdropper.
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Summarized by Copernic Summarizer
