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arXiv · 2610.16375

Pathfinder-BP: A Low-Latency Recursive Decoder for Topological Codes

Stefano Tinelli·Francisco Lázaro·Francisco García Herrero
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Abstract

We propose Pathfinder-BP, a recursive decoder for topological quantum codes that combines belief propagation with controlled bit-flipping. An initial BP pass identifies and permanently fixes high-confidence errors. Upon convergence failure, the decoder recursively explores alternative error patterns by tentatively flipping low-confidence variables. On surface codes, Pathfinder-BP achieves a noise threshold and logical error rate comparable to minimum-weight perfect matching (MWPM). A crucial advantage of Pathfinder-BP is its highly parallelizable structure, which yields a worst-case decoding latency quasi-linear in the code distance, making it a suitable candidate for low-latency hardware implementation.

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Stefano Tinelli, Francisco Lázaro, Francisco García Herrero. 2026-10-12. Pathfinder-BP: A Low-Latency Recursive Decoder for Topological Codes. https://arxiv.org/abs/2610.16375

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