Adaptive Multicarrier Quadrature Division Modulation for Continuous-Variable Quantum Key Distribution

Abstract

In a continuous-variable quantum key distribution (CVQKD) system, the information is conveyed by coherent state carriers. The quantum continuous variables are sent through a quantum channel, where the presence of the eavesdropper adds a white Gaussian noise to the transmission. The amount of tolerable noise and loss is a crucial point in CVQKD, since it determines the overall performance of the protocol, including the secure key rates and transmission distances. In this work, we propose the adaptive multicarrier quadrature division (AMQD) modulation technique for CVQKD. The method granulates the Gaussian random input into Gaussian subcarrier continuous variables in the encoding phase, which are then decoded by a continuous unitary transformation. The subcarrier coherent variables formulate Gaussian sub-channels from the physical link with strongly diverse transmission capabilities, which leads to significantly improved transmission efficiency, higher tolerable loss, and excess noise. We also investigate a modulation-variance adaption technique within the AMQD scheme, which provides optimal capacity-achieving communication over the sub-channels in the presence of a Gaussian noise.

v2: 37 pages, 8 figures, 1 table, added security proof

References in corpus (7)

• Unconditional optimality of Gaussian attacks against continuous-variable QKD
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• Adaptive Multicarrier Quadrature Division Modulation for Continuous-Variable Quantum Key Distribution

Cited by in corpus (4)

• Multiple Access Multicarrier Continuous-Variable Quantum Key Distribution
• Adaptive Multicarrier Quadrature Division Modulation for Continuous-Variable Quantum Key Distribution
• Gaussian Quadrature Inference for Multicarrier Continuous-Variable Quantum Key Distribution
• Statistical Quadrature Evolution by Inference for Continuous-Variable Quantum Key Distribution