Implementation of a twin-field quantum key distribution network faces limitations, including the low tolerance of interference errors for phase-matching type protocols and the strict constraint regarding intensity and probability for sending-or-not-sending type protocols. Here, we propose a two-photon twin-field quantum key distribution protocol and achieve twin-field-type two-photon interference through post-matching phase-correlated single-photon interference events. We exploit the non-interference mode as the code mode to highly tolerate interference errors, and the two-photon interference naturally removes the intensity and probability constraint. Therefore, our protocol can transcend the abovementioned limitations while breaking the secret key capacity of repeaterless quantum key distribution. Simulations show that for a four-user networks, under which each node with fixed system parameters can dynamically switch different attenuation links, the key rates of our protocol for all six links can either exceed or approach the secret key capacity. However, the key rates of all links are lower than the key capacity when using phase-matching type protocols. Additionally, four of the links could not extract the key when using sending-or-not-sending type protocols. We anticipate that our protocol can facilitate the development of practical and efficient quantum networks.
翻译:本研究提出了一种基于双光子的双场量子密钥分发协议,通过后匹配相位相关的单光子干涉事件实现了双场型双光子干涉。我们利用非干涉模式作为编码模式,高度容忍干涉误差,且双光子干涉自然消除了强度和概率约束。因此,我们的协议可以超越上述限制,同时打破无中继器量子密钥分发的秘密密钥容量。仿真结果显示,在四个用户的网路中,每个节点具有固定的系统参数,并可动态切换不同衰减链路,我们的协议在所有六个链路上的密钥速率可以超过或接近秘密密钥容量。但使用相位匹配型协议时,所有链路的密钥速率都低于密钥容量。另外,使用发送-不发送型协议时,其中四个链路不能提取密钥。我们预计我们的协议可以促进实用和高效的量子网络的发展。