FPGA-based microsystematic design of Gaussian modulation for continuous-variable quantum communication

Continuous-variable (CV) quantum communication is an important branch of quantum information technology and promises information-theoretical secure communication. High-performance and lightweight CV quantum devices are one of the keys to realizing quantum networks. Among them, the Gaussian-modulation module still has problems such as cumbersome photoelectric calibration and inconvenient use in the experimental stage, which introduces modulation noise and brings additional excess noise to the system, reducing the signal-to-noise ratio of the system and thus reducing system performance. To this end, by designing a field-programmable gate array and integrating all optical components (except the laser source), we achieved a miniaturized and low-cost Gaussian-modulation unit compatible with the existing fiber-optic communication infrastructure, realizing quantum signal modulation under adaptive photoelectric calibration. Taking CV quantum key distribution as the verification object, we analyzed the signal characteristics and the stability of the unit experimentally. The experimental results show that the proposed scheme exhibits quality Gaussian properties and correlations. Moreover, the temporal stability of the device is relatively high (the mean fluctuation is on the order of ${10}^{\ensuremath{-}31}$ and the variance fluctuation is 0.0363), which provides more possibilities for the subsequent popularization of quantum communication and the development of quantum information networks.