We consider quantum networks, where entangled photon pairs are distributed using fibre optic links from a centralized source to entangling nodes. The entanglement is then stored (via an entanglement swap) in entangling nodes' quantum memories until used in, e.g., distributed quantum computing, quantum key distribution, quantum sensing, and other applications. Due to the fibre loss, some photons are lost in transmission. Noise in the transmission link and the quantum memory also reduces fidelity. Thus, entangling nodes must keep updated records of photon-pair arrivals to each destination, and their use by the applications. This coordination requires classical information exchange between each entangled node pair. However, the same fibre link may not admit both classical and quantum transmissions, as the classical channels can generate enough noise (i.e., via spontaneous Raman scattering) to make the quantum link unusable. Here, we consider coordinating entanglement distribution using a standard Internet protocol (IP) network instead, and propose a control protocol to enable such. We analyse the increase in latency from transmission over an IP network, together with the effect of photon loss, quantum memory noise and buffer size, to determine the fidelity and rate of entangled pairs. We characterize the relationship between the latency of the non-ideal IP network and the decoherence time of the quantum memories, providing a comparison of promising quantum memory technologies.

翻译：我们研究量子网络，其中纠缠光子对通过光纤链路从中心化源分发至纠缠节点。随后，纠缠态通过纠缠交换存储在纠缠节点的量子存储器中，直至用于分布式量子计算、量子密钥分发、量子传感及其他应用。由于光纤损耗，部分光子在传输过程中丢失。传输链路及量子存储器中的噪声也会降低保真度。因此，纠缠节点必须持续更新记录每个目的地的光子对到达情况及其在应用中的使用状态。这种协调需要在每对纠缠节点之间进行经典信息交换。然而，同一光纤链路可能无法同时支持经典与量子传输，因为经典信道可能产生足够噪声（例如通过自发拉曼散射）导致量子链路失效。本文提出改用标准互联网协议网络协调纠缠分发，并设计一种控制协议以实现该方案。我们分析了通过IP网络传输带来的延迟增加，结合光子损耗、量子存储器噪声及缓冲区大小的影响，以确定纠缠对的保真度与生成速率。我们刻画了非理想IP网络延迟与量子存储器退相干时间的关系，并对具有前景的量子存储器技术进行了比较分析。