Intrinsic Heralding and Optimal Decoders for Non-Abelian Topological Order

Topological order (TO) provides a natural platform for storing and manipulating quantum information. However, its stability to noise has only been systematically understood for Abelian TOs. In this Letter, we exploit the nondeterministic fusion of non-Abelian anyons to inform active error-correction and design decoders where the fusion products, instead of flag qubits, herald the noise. This intrinsic heralding offers improved thresholds over those of Abelian counterparts. Furthermore, we use Bayesian inference to obtain a statistical mechanics model for fixed-point non-Abelian TOs with perfect measurements under any noise model, which yields the optimal threshold conditioned on measuring anyon syndromes. We numerically illustrate these results for D_{4}≅Z_{4}⋊Z_{2} TO. In particular, for non-Abelian charge noise and perfect syndrome measurement, we find a conditioned optimal threshold p_{c}=0.218(1), whereas an intrinsically heralded minimum-weight perfect matching (MWPM) decoder already gives p_{c}=0.208 42(2), outperforming standard honeycomb-lattice MWPM with p_{c}=0.158 60(1). Our Letter highlights how non-Abelian properties can enhance stability, rather than reduce it, and discusses potential generalizations for achieving fault tolerance.