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arXiv · 2212.04019

Silicon-based decoder for polarization-encoding quantum key distribution

Yongqiang Du·Xun Zhu·Xin Hua·Zhengeng Zhao·Xiao Hu·Yi Qian·Xi Xiao·Kejin Wei
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Abstract

Silicon-based polarization-encoding quantum key distribution (QKD) has been widely studied, owing to its low cost and robustness. However, prior studies have utilized off-chip devices to demodulate the quantum states or perform polarization compensation, given the difficulty of fabricating polarized independent components on the chip. In this paper, we propose a fully chip-based decoder for polarization-encoding QKD. The chip realizes a polarization state analyzer and compensates for the BB84 protocol without requiring additional hardware. It is based on a polarization-to-path conversion method that uses a polarization splitter-rotator. The chip was fabricated using a standard silicon photonics foundry; it has a compact design and is suitable for mass production. In the experimental stability test, an average quantum bit error rate of $0.56\%$ was achieved through continuous operation for 10 h without any polarization feedback. Furthermore, using the developed feedback algorithm, the chip enabled the automatic compensation of the fiber polarization drift, which was emulated by a random fiber polarization scrambler. In the case of the QKD demonstration, we obtained a finite-key secret rate of 240 bps over a fiber spool of 100 km. This study represents an important step toward the integrated, practical, and large-scale deployment of QKD systems.

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Yongqiang Du, Xun Zhu, Xin Hua, Zhengeng Zhao, Xiao Hu, Yi Qian, Xi Xiao, Kejin Wei. 2022-12-08. Silicon-based decoder for polarization-encoding quantum key distribution. https://arxiv.org/abs/2212.04019

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