High-speed operation of four-state continuous-variable quantum key distribution using quantum random numbers

Dabo Guo, Chao He, Tianhao Guo +3 more

Jian Zhou, Leixin Wu, Yanyan Feng +3 more

Xiunan Sun, Hao Liang

The continuous-variable quantum key distribution experimental system requires the randomness and speed of a Gaussian modulator. We present the hardware design for a Gaussian random number (GRN) generator based on the Box–Muller method, which can be implemented on a field-programmable gate array (FPGA). An external high-speed true random number generator application-specific integrated circuit (ASIC) is used to this end. The ASIC operates faster and more independently compared with other Gaussian algorithms based on a linear feedback shift register. The trigonometric and logarithmic functions are calculated using the nonuniform piecewise linear approximation. The calculation of the Gaussian random modulus and phase value is realized using this hardware. Compared with an arbitrary waveform generator, the GRN can be uploaded to a computer to estimate the security key rate. Furthermore, the GRN generator accurately provides a Gaussian probability density function that passes the Jarque–Bera inspection and Lilliefors tests. The proposed FPGA-based system is demonstrated to convert eight-channel 320-Mbps uniform random numbers to 40-MHz 16-bit GRN in real time. Finally, the control of the optical module and Gaussian modulation is realized via the FPGA-based outputs of four dual-channel, 16-bit, 1-giga samples per second digital-to-analog converters.

Peng Huang, Tao Wang, Rui Chen +3 more

Abstract Gaussian-modulated coherent-state (GMCS) continuous-variable quantum key distribution (CVQKD) protocol can allow authenticated users to share secret key with unconditional security. So far, all previous experimental implementations of GMCS CVQKD schemes are based on active modulations, i.e. amplitude and phase modulators and quantum random number generator (QRNG) are required. However, high-speed modulation with high extinction ratio and stability is challenging, which is extremely remarkable in chip-scale silicon photonic realization. While the passive-state-preparation (PSP) CVQKD scheme, which explores the intrinsic field fluctuations of a thermal source, avoids the uses of active modulations and QRNG. In this paper, we experimentally realize the intact PSP CVQKD through a realistic optical fiber channel using off-the-shelf amplified spontaneous emission source. In particular, specially designed frame synchronization method is used to build the correlation between the data measured from the two legitimate parties, and excess noise are synthetically controlled to generate secure secret keys at the metro-area distances when considering the practical and non-negligible finite-size effects under collective Gaussian attacks. Due to the avoidance of modulators and QRNG, the passive state encoding scheme provides a promising direction of applicable high-speed, chip-based and even sunlight-based CVQKD with less cost and complexity.

Bangjie Su, Yixuan Wang, Jian Zhou +4 more

Jiayan Fu, Bangjie Su, Jian Zhou +2 more