Handling fabrication defects in hex-grid surface codes

2025/08/11 by Oscar Higgott, Higgott, Oscar, Benjamin Anker +5 · 3 voices · 2 citations
Computer Science · #Advanced Data Storage Technologies #Quantum Computing Algorithms and Architecture #Quantum-Dot Cellular Automata #quant-ph

paper · pdf · doi:10.48550/arxiv.2508.08116

openalex publication_date 2025/08/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Recent work has shown that a hexagonal grid qubit layout, with only three couplers per qubit, is sufficient to implement the surface code with performance comparable to that of a traditional four-coupler layout [McEwen et al., 2023]. In this work we propose a method for handling broken qubits and couplers even in hex-grid surface code architectures, using an extension of the LUCI framework [Debroy et al., 2024]. We show that for isolated broken qubits, the circuit distance drops by one, while for isolated broken couplers, the distance drops by one in one or both bases. By providing a viable dropout strategy, we have removed a critical roadblock to the implementation of hexagonal qubit grids in hardware for large-scale quantum error correction.

Citations

• Excising dead components in the surface code using minimally invasive alterations: A performance study
• Architectural mechanisms of a universal fault-tolerant quantum computer
• Halma: a routing-based technique for defect mitigation in quantum error correction
• Demonstrating dynamic surface codes
• Snakes and Ladders: Adapting the surface code to defects
• LUCI in the Surface Code with Dropouts
• Quantum error correction below the surface code threshold
• Low-Overhead Defect-Adaptive Surface Code with Bandage-Like Super-Stabilizers
• Fault-Tolerant Hastings-Haah Codes in the Presence of Dead Qubits
• Less Bacon More Threshold
• Relaxing Hardware Requirements for Surface Code Circuits using Time-dynamics
• Quantum computing is scalable on a planar array of qubits with fabrication defects
• Optimal complexity correction of correlated errors in the surface code
• Topological quantum memory
• The Heisenberg Representation of Quantum Computers

Cited by

• Scalable quantum error correction tailored for a heavy-hex qubit array
• Automated Compilation Including Dropouts: Tolerating Defective Components in Stabiliser Codes
• A dynamic circuit for the honeycomb Floquet code

Discussions

• Using time-dynamics, the surface code can be embedded on a hexagonal lattice rather than a square lattice. In our new paper, we show that these hex-grid circuits can still be adapted to broken qubits [bsky, 14 points, 0 comments]
• Looks like 3-coupler / hex implementation of the surface code can now tolerate dropout! www.arxiv.org/abs/2508.08116 [bsky, 8 points, 1 comments]
• Check out our new work on how to make the surface code on a hexagonal grid robust to dead components: www.arxiv.org/abs/2508.08116 It turns out adding weight-1 checks to LUCI gives you a lot of new fr [bsky, 8 points, 0 comments]

Related

• LUCI in the Surface Code with Dropouts
• Optimized Measurement Schedules for the Surface Code with Dropout
• Low-Overhead Defect-Adaptive Surface Code with Bandage-Like Super-Stabilizers
• Snakes and Ladders: Adapting the surface code to defects
• Demonstrating dynamic surface codes