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Bell's Inequality, Random Sequence, and Quantum Key Distribution

W. -Y. Hwang
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Abstract

The Ekert 91 quantum key distribution (QKD) protocol appears to be secure whatever devices legitimate users adopt for the protocol, as long as the devices give a result that violates Bell's inequality. However, this is not the case if they ignore non-detection events because Eve can make use of the detection-loophole, as Larrson showed. We show that even when legitimate users take into account non-detection events Eve can successfully eavesdrop if the QKD system has been appropriately designed by the manufacturer. A loophole utilized here is that of `free-choice' (or `real randomness'). Local QKD devices with pseudo-random sequence generator installed in them can apparently violate Bell's inequality.

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W. -Y. Hwang. 2005-03-22. Bell's Inequality, Random Sequence, and Quantum Key Distribution. https://doi.org/10.1103/physreva.71.052329

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