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A decoy-state protocol for quantum cryptography with 4 intensities of coherent states

Xiang-Bin Wang
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Abstract

In order to beat any type of photon-number-splitting attack, we propose a protocol for quantum key distributoin (QKD) using 4 different intensities of pulses. They are vacuum and coherent states with mean photon number $μ,μ'$ and $μ_s$. $μ_s$ is around 0.55 and this class of pulses are used as the main signal states. The other two classes of coherent states ($μ,μ'$) are also used signal states but their counting rates should be studied jointly with the vacuum. We have shown that, given the typical set-up in practice, the key rate from the main signal pulses is quite close to the theoretically allowed maximal rate in the case given the small overall transmittance of $10^{-4}$.

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Xiang-Bin Wang. 2005-02-21. A decoy-state protocol for quantum cryptography with 4 intensities of coherent states. https://doi.org/10.1103/physreva.72.012322

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