Magic-state functional units mapping and scheduling multi-level distillation circuits for fault-tolerant quantum architectures

• Published in: 2018 51st Annual IEEE/ACM International Symposium on Microarchitecture (MICRO) pp. 828 - 840
• Main Authors: Ding, Yongshan, Holmes, Adam, Javadi-Abhari, Ali, Franklin, Diana, Martonosi, Margaret, Chong, Frederic T.
• Format: Conference Proceeding
• Language: English
• Published: Piscataway, NJ, USA IEEE Press 01.10.2018; IEEE
• Series: ACM Conferences
• Subjects: Error analysis; Error correction codes; Logic gates; Magic State Distillation; Production facilities; Protocols; Quantum Computing; Quantum Error Correction; Surface Code; magic state distillation; surface code; quantum error correction; quantum computing
• DOI: 10.1109/MICRO.2018.00072
• ISBN: 9781538662403; 153866240X

Quantum computers have recently made great strides and are on a long-term path towards useful fault-tolerant computation. A dominant overhead in fault-tolerant quantum computation is the production of high-fidelity encoded qubits, called magic states, which enable reliable error-corrected computation. We present the first detailed designs of hardware functional units that implement space-time optimized magic-state factories for surface code error-corrected machines. Interactions among distant qubits require surface code braids (physical pathways on chip) which must be routed. Magic-state factories are circuits comprised of a complex set of braids that is more difficult to route than quantum circuits considered in previous work [1]. This paper explores the impact of scheduling techniques, such as gate reordering and qubit renaming, and we propose two novel mapping techniques: braid repulsion and dipole moment braid rotation. We combine these techniques with graph partitioning and community detection algorithms, and further introduce a stitching algorithm for mapping subgraphs onto a physical machine. Our results show a factor of 5.64 reduction in space-time volume compared to the best-known previous designs for magic-state factories.