Handling fabrication defects in hex-grid surface codes

• URL: http://arxiv.org/abs/2508.08116v1
• Date: Mon, 11 Aug 2025 15:55:35 GMT
• Title: Handling fabrication defects in hex-grid surface codes
• Abstract summary: We propose a method for handling broken qubits and couplers even in hex-grid surface code architectures.<n>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.
• Score: 0.27907620376288694
• License: http://creativecommons.org/licenses/by/4.0/
• 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.

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