Abstract
Performance analysis of continuous-variable quantum key distribution (CVQKD) has been one of the focuses of quantum communications. In this paper, we propose an approach to enhancing the secret rate of CVQKD with the multi-core fiber (MCF) system that transmits multiple spatial modes simultaneously. The excess noise contributed by the inter-core crosstalk between cores can be effectively suppressed by quantum channel wavelength management, leading to the performance improvement of the MCF-based CVQKD system. In the security analysis, we perform numerical simulations for the Gaussian-modulated coherent state CVQKD protocol, considering simultaneously the extra insert loss of fan-in/fan-out (FIFO), which is the extra optical device that should be used at the input and the output of the fiber. Simulation results show that the performance of the one-way and two-way protocols for each core are slightly degraded because of the insert loss of the FIFO, but the total secret key rate can be increased, whereas the performance of the measurement-device-independent CVQKD protocol will be degraded due to the effect of the insert loss of the FIFO. These results may provide theoretical foundation for the space-division multiplexing CVQKD system.
Highlights
Since Bennett and Brassard presented the first quantum key distribution (QKD) protocol, i.e., BB84 protocol [1], lots of groundbreaking researches of QKD have emerged
We have demonstrated the characteristics of the multi-core fiber (MCF)-based continuous-variable quantum key distribution (CVQKD) system
We have proposed the performance analysis of the MCF-based CVQKD
Summary
Since Bennett and Brassard presented the first quantum key distribution (QKD) protocol, i.e., BB84 protocol [1], lots of groundbreaking researches of QKD have emerged. One realizing approach of SDM is to use multi-core fiber (MCF) Through using it, another multiplexing dimensionality—spatial dimension—is able to be fully utilized to increase the secret key rate. We propose the MCF-based CVQKD scheme, which can increase the secret key rate via transmitting multiple spatial modes simultaneously. We perform simulations based on the Gaussian-modulated coherent state CVQKD protocol and numeric results show that the performance of the one-way and two-way protocols for each core may be slightly degraded because of the insert loss of the FIFO, but the total secret key rate can be significantly improved.
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