@article{204356,
  author = {James Ang and Gabriella Carini and Yanzhu Chen and Isaac Chuang and Michael DeMarco and Sophia Economou and Alec Eickbusch and Andrei Faraon and Kai-Mei Fu and Steven Girvin and Michael Hatridge and Andrew Houck and Paul Hilaire and Kevin Krsulich and Ang Li and Chenxu Liu and Yan Liu and Margaret Martonosi and David McKay and James Misewich and Mark Ritter and Robert Shoelkopf and Smuel Stein and Sara Sussman and Hong Tang and Wei Tang and Teague Tomesh and Norm Tubman and Chen Wang and Nathan Wiebe and Yong-Xin Yao and Dillon Yost and Yiyi Zhou},
  title = {Architectures for Multinode Superconducting Quantum Computers},
  abstract = {<p>Many proposals to scale quantum technology rely on modular or distributed designs where individual quantum processors, called nodes, are linked together to form one large multinode quantum computer (MNQC). One scalable method to construct an MNQC is using superconducting quantum systems with optical interconnects. However, a limiting factor of these machines will be internode gates, which may be two to three orders of magnitude noisier and slower than local operations. Surmounting the limitations of internode gates will require a range of techniques, including improvements in entanglement generation, the use of entanglement distillation, and optimized software and compilers, and it remains unclear how improvements to these components interact to affect overall system performance, what performance from each is required, or even how to quantify the performance of each. In this paper, we employ a {\textquoteleft}co-design{\textquoteright} inspired approach to quantify overall MNQC performance in terms of hardware models of internode links, entanglement distillation, and local architecture. In the case of superconducting MNQCs with microwave-to-optical links, we uncover a tradeoff between entanglement generation and distillation that threatens to degrade performance. We show how to navigate this tradeoff, lay out how compilers should optimize between local and internode gates, and discuss when noisy quantum links have an advantage over purely classical links. Using these results, we introduce a roadmap for the realization of early MNQCs which illustrates potential improvements to the hardware and software of MNQCs and outlines criteria for evaluating the landscape, from progress in entanglement generation and quantum memory to dedicated algorithms such as distributed quantum phase estimation. While we focus on superconducting devices with optical interconnects, our approach is general across MNQC implementations.</p>
},
  year = {2022},
  journal = {arXiv},
  month = {12/2022},
  url = {https://arxiv.org/abs/2212.06167},
}