Fig. 4: Decoding performance on Circuit Type I.
a,b, Logical accuracy versus circuit depth using surface code with code distance d = 3 (a) and d = 5 (b) for MCCD (red), MLE (orange), BP-OSD (green) and MWPM (blue) decoders. c,d, Wall time taken to decode one syndrome trajectory in log scale with increasing circuit depth for a d = 3 (c) and d = 5 (d) surface code. We evaluate each decoder over 20 independent runs. In each run, we randomly sample 1,000 syndrome trajectories from Type I circuits and average them to obtain a run-level performance estimate. We report the mean across the 20 runs, with error bars showing s.e.m.
