论文标题
双场量子键分布在光通道上具有不对称损失的基本实验证明
Proof-of-principle experimental demonstration of twin-field quantum key distribution over optical channels with asymmetric losses
论文作者
论文摘要
双场（TF）量子密钥分布（QKD）具有很高的吸引力，因为它可以超过无量子中继器的点对点QKD的基本限制。许多理论和实验研究表明，TFQKD在长途交流中的优越性。 TFQKD的所有先前实验实现都是在具有对称损失的光通道上完成的。但实际上，尤其是在网络环境中，用户与中间节点之间的距离可能会大不相同。在本文中，我们在具有不对称损失的光通道上对TFQKD进行了初步证明。我们比较了两种补偿策略，即（1）应用不对称的信号强度和（2）增加额外的损失，并验证该策略（1）提供了更好的关键率。此外，损失越高，它可以实现的关键率越高。通过应用不对称信号强度，具有不对称通道损失的TFQKD不仅超过了50 dB总损失的点对点QKD的关键率的基本限制，而且关键率高达2.918美元\ times10^{ - 6} $ 56 dB的总损失。而没有使用策略（2）获得56 dB损失的策略。 TFQKD随着不对称通道损失的增加的关键率和扩大的距离覆盖范围可确保其在长距离量子网络中的优势。
Twin-field (TF) quantum key distribution (QKD) is highly attractive because it can beat the fundamental limit of secret key rate for point-to-point QKD without quantum repeaters. Many theoretical and experimental studies have shown the superiority of TFQKD in long-distance communication. All previous experimental implementations of TFQKD have been done over optical channels with symmetric losses. But in reality, especially in a network setting, the distances between users and the middle node could be very different. In this paper, we perform a first proof-of-principle experimental demonstration of TFQKD over optical channels with asymmetric losses. We compare two compensation strategies, that are (1) applying asymmetric signal intensities and (2) adding extra losses, and verify that strategy (1) provides much better key rate. Moreover, the higher the loss, the more key rate enhancement it can achieve. By applying asymmetric signal intensities, TFQKD with asymmetric channel losses not only surpasses the fundamental limit of key rate of point-to-point QKD for 50 dB overall loss, but also has key rate as high as $2.918\times10^{-6}$ for 56 dB overall loss. Whereas no keys are obtained with strategy (2) for 56 dB loss. The increased key rate and enlarged distance coverage of TFQKD with asymmetric channel losses guarantee its superiority in long-distance quantum networks.
