Surface-Code Thresholds and Qubit Footprints in Shuttling-Based Spin-Qubit Railways
Abstract
We present a fault-tolerant mapping of rotated surface codes onto a silicon spin-qubit railway architecture, utilizing electron shuttling to resolve the wiring fan-out bottleneck. Employing circuit-level noise modeling, we evaluate threshold performances across various noise biases. We demonstrate that shuttling check qubits instead of data qubits fundamentally improves system thresholds. Crucially, under a noise model biased towards dephasing for spin-qubit shuttling, the non-CSS XZZX surface code outperforms standard CSS variants. By tailoring the topological code to this specific inherent bias, we show that the Megaquop footprint is achievable with a distance 7 code requiring a physical error rate, highlighting a pathway for substantial hardware reductions in early fault-tolerant quantum processors.
Cite
@article{arxiv.2605.05881,
title = {Surface-Code Thresholds and Qubit Footprints in Shuttling-Based Spin-Qubit Railways},
author = {Arun John Moncy and Reza Dastbasteh and Josu Etxezarreta Martinez and Ryo Nagai and Pedro M. Crespo and Normann Mertig and Charles Smith and Ruben M. Otxoa},
journal= {arXiv preprint arXiv:2605.05881},
year = {2026}
}
Comments
14 pages, 12 figures