This research proposal seeks to experimentally validate the 𝑁=18 stability invariant as the geometric origin of the Λ ≈2.1 logical error suppression factor recently observed on the 105-qubit Willow processor. We propose a benchmarking series to observe the "isostatic closure" of a distance-7 surface code lattice, where the degrees of freedom (2𝑁=36) exactly balance the bulk stabilizers (𝑑−12=36).
Peter Stewart (Mon,) studied this question.