Free-space quantum key distribution (QKD) can be very attractive due to the possibility of its flexible and rapid deployment. In spite of the advantages of free-space transmission, there is still a risk of encountering bad weather such as fog. Here we experimentally demonstrate free-space QKD using continuous variables under foggy conditions and estimate achievable transmission distances based on the experimental results. Pessimistically, a weather condition that has visibility of 1 km allows about 0.6-km transmission. An optimistic result, on the other hand, shows that a transmission distance of 1.8 km at visibility of 1.5 km can be achieved. The results suggest that free-space continuous-variable quantum communication systems are potentially applicable in the presence of fog.

中文翻译：

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通过雾连续可变量子密钥分发的可行性

由于其灵活和快速部署的可能性，自由空间量子密钥分发 (QKD) 可能非常有吸引力。尽管自由空间传输具有优势，但仍存在遇到雾等恶劣天气的风险。在这里，我们在有雾条件下使用连续变量实验证明了自由空间 QKD，并根据实验结果估计了可实现的传输距离。悲观地说，能见度为 1 公里的天气条件允许大约 0.6 公里的传输。另一方面，乐观的结果表明，在能见度为 1.5 公里的情况下，可以实现 1.8 公里的传输距离。结果表明，自由空间连续可变量子通信系统可能适用于存在雾的情况。