发表机构
Imperial College London（帝国理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用ZX演算构建混合综合征提取协议，应用于分布式表面码晶格手术，在无本地噪声时达到50%接口擦除阈值，并提升接口距离，适用于低噪声场景。
AI 中文摘要
将基于物质的量子处理单元（QPU）联网为扩展容错量子计算机提供了一条有前景的途径。这需要在光子链路上执行分布式逻辑操作，由于光子损失和概率性线性光学操作，其噪声特征与本地QPU不同且更强。基于测量和融合的量子计算被设计为对损失和概率性光子操作具有鲁棒性，这表明它们可以在联网QPU之间的接口处补充基于电路的纠错。我们使用ZX演算变换来构建混合综合征提取协议，并将其应用于分布式旋转表面码晶格手术，证明了在无本地噪声的情况下，若干协议达到了50%的接口擦除阈值，包括使用融合贝尔对的基于电路的晶格手术和使用线性簇态的混合协议。相对于直接的贝尔对接口几何结构，混合协议将合并可观测量的接口距离从d+1增加到2d+1，并将垂直可观测量的接口距离从⌊(d+1)/2⌋恢复到d。我们计算了使用截断资源态时阈值如何降低，并绘制了在资源态错误、本地电路噪声和融合擦除下的可纠正区域。然后，我们将这些擦除阈值转换为光子损失阈值，并使用融合提升来探测亚阈值性能。在电路和资源态错误率为10^-3时，本地错误在很大程度上掩盖了接口距离优势。当本地噪声降低到10^-4及以下时，线性链协议随着擦除的减少而更快地改进，这表明接口距离增强在低本地噪声区域中是有效的。
英文摘要
Networking matter-based quantum processing units (QPUs) offers a promising route to scaling fault-tolerant quantum computers. This requires distributed logical operations to be performed across photonic links, where noise is characteristically different from and stronger than in local QPUs owing to photon loss and probabilistic linear-optical operations. Measurement- and fusion-based quantum computing are designed to be robust against loss and probabilistic photonic operations, suggesting they could complement circuit-based error correction at the interface between networked QPUs. We use ZX calculus transformations to construct hybrid syndrome extraction protocols and apply them to distributed rotated surface code lattice surgery, demonstrating that several protocols attain a $50\%$ interface-erasure threshold when local noise is absent, including circuit-based lattice surgery using fused Bell pairs and hybrid protocols using linear cluster states. Relative to a straight Bell-pair interface geometry, the hybrid protocols increase the merge-observable interface distance from $d+1$ to $2d+1$ and restore the perpendicular-observable interface distance from $\lfloor(d+1)/2\rfloor$ to $d$. We calculate how the threshold decreases when using truncated resource states and map correctable regions under resource-state errors, local circuit noise, and fusion erasure. We then convert these erasure thresholds into photon-loss thresholds and probe subthreshold performance using fusion boosting. At circuit and resource-state error rates of $10^{-3}$, local errors largely mask the interface-distance advantage. As local noise is reduced to $10^{-4}$ and below, the linear-chain protocols improve more rapidly with decreasing erasure, suggesting that interface distance enhancements are effective in low local noise regimes.
Comments31 pages, 20 figures
