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：孪生场量子密钥分发网络的实现面临多重限制，包括相位匹配型协议对干涉误差的低容忍度，以及发送不发送型协议对强度和概率的严格约束。本文提出一种双光子孪生场量子密钥分发协议，通过后匹配的相位关联单光子干涉事件实现孪生场型双光子干涉。我们利用非干涉模式作为编码模式以高度容忍干涉误差，而双光子干涉则自然消除了强度与概率约束。因此，该协议在突破无中继量子密钥分发密钥容量的同时，能够超越上述限制。仿真结果表明，在四用户网络中，固定系统参数的每个节点可动态切换不同衰减链路，本协议在所有六条链路上的密钥速率均能超过或接近密钥容量。然而，采用相位匹配型协议时所有链路密钥速率均低于密钥容量；采用发送不发送型协议时，四条链路甚至无法提取密钥。我们预期该协议将推动实用化高效量子网络的发展。