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A practical limitation for continuous-variable quantum cryptography using coherent states

Ryo Namiki·Takuya Hirano
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Abstract

In this letter, first, we investigate the security of a continuous-variable quantum cryptographic scheme with a postselection process against individual beam splitting attack. It is shown that the scheme can be secure in the presence of the transmission loss owing to the postselection. Second, we provide a loss limit for continuous-variable quantum cryptography using coherent states taking into account excess Gaussian noise on quadrature distribution. Since the excess noise is reduced by the loss mechanism, a realistic intercept-resend attack which makes a Gaussian mixture of coherent states gives a loss limit in the presence of any excess Gaussian noise.

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Ryo Namiki, Takuya Hirano. 2004-03-16. A practical limitation for continuous-variable quantum cryptography using coherent states. https://doi.org/10.1103/physrevlett.92.117901

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