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Security improvement of using modified coherent state for quantum cryptography

Y. J. Lu·Luobei Zhu·Z. Y. Ou
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Abstract

Weak coherent states as a photon source for quantum cryptography have limit in secure data rate and transmission distance because of the presence of multi-photon events and loss in transmission line. Two-photon events in a coherent state can be taken out by a two-photon interference scheme. We investigate the security issue of utilizing this modified coherent state in quantum cryptography. A 4 dB improvement in secure data rate or a nearly two-fold increase in transmission distance over the coherent state are found. With a recently proposed and improved encoding strategy, further improvement is possible.

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Y. J. Lu, Luobei Zhu, Z. Y. Ou. 2005-01-30. Security improvement of using modified coherent state for quantum cryptography. https://doi.org/10.1103/physreva.71.032315

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