We present a quantum key distribution system with a 2.5~GHz repetition rate using a three-state time-bin protocol combined with a one-decoy approach. Taking advantage of superconducting single-photon detectors optimized for quantum key distribution and ultra low-loss fiber, we can distribute secret keys at a maximum distance of 421~km and obtain secret key rates of 6.5~bps over 405~km.

中文翻译：

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在421 km的光纤上安全分配量子密钥

我们提出了一种使用三态时间仓协议结合一诱饵方法的，具有2.5〜GHz重复率的量子密钥分配系统。利用针对量子密钥分配和超低损耗光纤优化的超导单光子探测器，我们可以在421〜km的最大距离内分配秘密密钥，并在405〜km范围内获得6.5〜bps的秘密密钥速率。