Low-valency scalable quantum error correction with a dynamic compass code

Jun Zen; Xanda C. Kolesnikow; Campbell K. McLauchlan; Georgia M. Nixon; Thomas R. Scruby; Seok-Hyung Lee; Stephen D. Bartlett; Benjamin J. Brown; Robin Harper

arXiv · 2604.14299

Low-valency scalable quantum error correction with a dynamic compass code

Jun Zen·Xanda C. Kolesnikow·Campbell K. McLauchlan·Georgia M. Nixon·Thomas R. Scruby·Seok-Hyung Lee·Stephen D. Bartlett·Benjamin J. Brown·Robin Harper

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Abstract

The ongoing development of hardware that is capable of reliably executing general quantum algorithms requires quantum error-correcting codes that are both practical for realisation and rapidly reduce logical error rates as they are scaled up. Here we introduce the dynamic compass code, a code that can be implemented with a modest footprint on the heavy-hex lattice while also demonstrating a threshold. The dynamic code is obtained by choosing a novel measurement schedule for the syndrome extraction circuit of the heavy-hex subsystem code. We numerically evaluate its performance and observe that different choices of schedule can provide a trade-off in protection against logical errors in the $X$ vs $Z$ basis. We also demonstrate that this new measurement schedule provides the code with a threshold for stability experiments. We finally show how the dynamic compass code could be used for fault-tolerant logic by illustrating lattice surgery between code patches.

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Jun Zen, Xanda C. Kolesnikow, Campbell K. McLauchlan, Georgia M. Nixon, Thomas R. Scruby, Seok-Hyung Lee, Stephen D. Bartlett, Benjamin J. Brown, Robin Harper. 2026-04-15. Low-valency scalable quantum error correction with a dynamic compass code. https://arxiv.org/abs/2604.14299

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