Experimental error filtration for quantum communication over highly noisy channels.
Error filtration is a method for encoding the quantum state of a single particle into a higher dimensional Hilbert space in such a way that it becomes less sensitive to noise. We have realized a fiber optics demonstration of this method and illustrated its potentialities by carrying out the optical part of a quantum key distribution scheme over a line whose phase noise is too high for a standard implementation of BB84 to be secure. By filtering out the noise, a bit error rate of 15.3% +/- 0.1%, which is beyond the security limit, can be reduced to 10.6% +/- 0.1%, thereby guaranteeing the cryptographic security.
Lamoureux
L-P
LP
Quantum Information and Communication, Ecole Polytechnique, CP 165/59, Université Libre de Bruxelles, Avenue F. D. Roosevelt 50, 1050 Brussels, Belgium.
Brainis
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Cerf
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Emplit
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Haelterman
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Massar
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