Much like classical supercomputers, scaling up quantum computers requires an optical interconnect. However, signal attenuation leads to irreversible qubit loss, making quantum interconnect design guidelines and metrics different from conventional computing. Inspired by the classical Dragonfly topology, we propose a multi-group structure where the group switch routes photons emitted by computational end nodes to the group's shared pool of Bell state analyzers (which conduct the entanglement swapping that creates end-to-end entanglement) or across a low-diameter path to another group. We present a full-stack analysis of system performance, a combination of distributed and centralized protocols, and a resource scheduler that plans qubit placement and communications for large-scale, fault-tolerant systems. We implement a prototype three-node switched interconnect and create two-hop entanglement with fidelities of at least 0.6. Our design emphasizes reducing network hops and optical components to simplify system stabilization while flexibly adjusting optical path lengths. Based on evaluated loss and infidelity budgets, we find that moderate-radix switches enable systems meeting expected near-term needs, and large systems are feasible. Our design is expected to be effective for a variety of quantum computing technologies, including ion traps and superconducting qubits with appropriate wavelength transduction.

翻译：与经典超级计算机类似，量子计算机的规模化扩展同样需要光学互连。然而，信号衰减会导致不可逆的量子比特损耗，这使得量子互连的设计准则和评估指标与传统计算系统存在本质差异。受经典Dragonfly拓扑结构启发，我们提出一种多组群架构：组内交换机将计算终端节点发射的光子路由至该组共享的贝尔态分析器池（通过纠缠交换实现端到端纠缠生成），或通过低直径路径跨组传输。我们提出了完整的系统性能全栈分析框架，结合分布式与集中式协议，并设计了面向大规模容错系统的资源调度器，用于规划量子比特布局与通信方案。我们实现了三节点交换互连原型系统，成功创建了保真度不低于0.6的双跳纠缠。本设计通过减少网络跳数和光学组件来简化系统稳定化需求，同时支持光学路径长度的灵活调节。基于对损耗与保真度误差容限的评估，我们发现中等基数交换机足以满足近期预期需求，且大规模系统具备可行性。该架构预期可适用于多种量子计算技术平台，包括离子阱与经过波长转换的超导量子比特系统。