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Quantum cryptography

Code-breakers confounded

Nature volume 421, pages 224–225 (2003)Cite this article

Coherent-state quantum cryptography holds the promise of efficient, secure communication. An experimental demonstration shows that a secure key to the code can be exchanged, even if there is a large transmission loss.

Quantum cryptography makes use of the unusual properties of quantum mechanics to protect encoded information. In trying to listen in on a message sent through a properly designed quantum communication channel, an eavesdropper will inevitably disturb the signal and thereby reveal his or her presence. The quantum cryptographic schemes that have been explored so far have made use of either single photons or very weak light pulses. Could it be possible to use more intense light pulses containing many photons and still take advantage of quantum mechanics to protect secret information? In their paper on page 238 of this issue, Frédéric Grosshans and colleagues1 show that it is. They have constructed a table-top system that encodes information in particular quantum states of light that contain several hundred photons each, then transmits them and decodes the information. This could lead to a faster and more efficient way of using quantum mechanics to send encrypted information.

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References

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  1. Department of Physics, Hunter College, City University of New York, 695 Park Avenue, New York, 10021, New York, USA

    Mark Hillery

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  1. Mark Hillery
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Correspondence to Mark Hillery.

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Hillery, M. Code-breakers confounded. Nature 421, 224–225 (2003). https://doi.org/10.1038/421224a

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  • DOI: https://doi.org/10.1038/421224a

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