Twin-field (TF) quantum key distribution (QKD) fundamentally alters the rate-distance relationship of QKD, offering the scaling of a single-node quantum repeater. Although recent experiments have demonstrated the new opportunities for secure long-distance communications allowed by TF-QKD, formidable challenges remain to unlock its true potential. Previous demonstrations have required intense stabilization signals at the same wavelength as the quantum signals, thereby unavoidably generating Rayleigh scattering noise that limits the distance and bit rate. Here, we introduce a dual-band stabilization scheme that overcomes past limitations and can be adapted to other phase-sensitive single-photon applications. Using two different optical wavelengths multiplexed together for channel stabilization and protocol encoding, we develop a setup that provides repeater-like key rates over communication distances of 555 km and 605 km in the finite-size and asymptotic regimes respectively and increases the secure key rate at long distance by two orders of magnitude to values of practical relevance.

双场 (TF) 量子密钥分配 (QKD) 从根本上改变了 QKD 的速率-距离关系，提供了单节点量子中继器的缩放。尽管最近的实验已经证明了 TF-QKD 为安全远程通信带来的新机遇，但要释放其真正潜力仍然面临着巨大的挑战。先前的演示需要与量子信号具有相同波长的强烈稳定信号，从而不可避免地产生限制距离和比特率的瑞利散射噪声。在这里，我们介绍了一种双波段稳定方案，它克服了过去的限制，可以适应其他相敏单光子应用。使用两个不同的光波长复用在一起进行通道稳定和协议编码，