To scale quantum computers to useful levels, we must build networks of quantum computational nodes that can share entanglement for use in distributed forms of quantum algorithms. In one proposed architecture, node-to-node entanglement is created when nodes emit photons entangled with stationary memories, with the photons routed through a switched interconnect to a shared pool of Bell state analyzers (BSAs). Designs that optimize switching circuits will reduce loss and crosstalk, raising entanglement rates and fidelity. We present optimal designs for switched interconnects constrained to planar layouts, appropriate for silicon waveguides and Mach-Zehnder interferometer (MZI) $2 \times 2$ switch points. The architectures for the optimal designs are scalable and algorithmically structured to pair any arbitrary inputs in a rearrangeable, non-blocking way. For pairing $N$ inputs, $N(N - 2)/4$ switches are required, which is less than half of number of switches required for full permutation switching networks. An efficient routing algorithm is also presented for each architecture. These designs can also be employed in reverse for entanglement generation using a shared pool of entangled paired photon sources.

翻译：为将量子计算机扩展至实用化水平，我们需构建量子计算节点网络，使其能够共享纠缠态以实现分布式量子算法。在一种提出的架构中，节点间纠缠通过节点发射与静态存储器纠缠的光子产生，这些光子经由交换互连路由至共享贝尔态分析器池。优化交换电路设计可降低损耗和串扰，从而提高纠缠速率与保真度。本文提出了适用于平面布局的最优交换互连设计，特别适配硅波导和马赫-曾德尔干涉仪（MZI）$2 \times 2$ 交换节点。这些最优设计的架构具有可扩展性，并通过算法结构化方式，以可重排无阻塞模式配对任意输入。对于 $N$ 个输入的配对，所需交换节点数量为 $N(N - 2)/4$，不足完全置换交换网络所需交换节点数的一半。此外，针对每种架构还提出了高效的路由算法。这些设计也可反向应用于利用共享纠缠光子对源生成纠缠态。