High-speed continuous-variable quantum key distribution over atmospheric turbulent channels

Qu, Zhen; Djordjević, Ivan B.

doi:10.1117/12.2250213

Cited by 4 publications

(1 citation statement)

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“…In this paper, we have addressed a long-standing open problem in continuous-variable quantum key distribution (CV-QKD), by establishing a security proof for discretemodulation protocols. Even though many experiments have been performed on discrete-modulation CV-QKD with multiple constellation points (see, e.g., [56][57][58]), no security proofs have been available for them, and the expected key-rate calculations reported based on measured homodyne statistics have been based on assuming Gaussian attacks, which are not known to be optimal for discrete-modulation CV-QKD. We have introduced a discrete-modulation protocol and then obtained rigorous lower bounds on the secret-key rates, secure against collective attacks in the asymptotic key-length regime.…”

Section: Discussionmentioning

confidence: 99%

Asymptotic security of discrete-modulation protocols for continuous-variable quantum key distribution

Kaur,

Guha,

Wilde

2019

Preprint

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We consider discrete-modulation protocols for continuous-variable quantum key distribution (CV-QKD) that employ a modulation constellation consisting of a finite number of coherent states and that use a homodyne-detection receiver. We establish a security proof for collective attacks in the asymptotic regime, and we provide a formula for an achievable secret-key rate. Previous works established security proofs for Gaussian-modulation CV-QKD protocols or for discrete-modulation protocols with two or three coherent states. The main constituents of our approach include approximating a complex, isotropic Gaussian probability distribution by a finite-size Gauss-Hermite constellation, applying entropic continuity bounds, and leveraging previous security proofs for Gaussianmodulation protocols. As an application of our method, we calculate secret-key rates achievable over a pure-loss bosonic channel. Our results indicate that in the high-loss regime and for sufficiently large constellation size, the achievable key rates scale optimally, i.e., proportional to the channel's transmissivity, and they approach the rates achieved by a Gaussian-modulation protocol as the constellation size is increased.

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Section: Discussionmentioning

confidence: 99%