Fig. 2: Distance scaling experiment.
From: Scaling and logic in the colour code on a superconducting quantum processor
a, Detection probability Pd as a function of QEC cycle n for individual stabilizers (faded lines) and their average (solid line) for an X-basis state-preservation experiment in a distance-5 colour code. Weight-6 stabilizers are coloured in red and weight-4 stabilizers are coloured in gold. b, Detection probability for each tile of the distance-5 colour code, averaged over cycles and bases. c, Measured logical error PL for distance-3 (green triangles) and distance-5 (blue pentagons) codes averaged over the X and Z bases. Faded symbols correspond to individual distance-3 subsets. The solid lines, shown for the averaged distance-3 code and the distance-5 code, are fits to \({P}_{{\rm{L}}}={\varepsilon }_{0}\times {(1-2\times {\varepsilon }_{d})}^{n}+1/2\), with fitting parameters ε0 and εd. d, Logical error per cycle, εd, compared with code distance, d. Same symbols as in c. e, Relative contributions of different error sources to the error budget for the colour code: CZ errors (CZ); errors from spurious interactions during two-qubit gates (CZ stray int.); leakage errors during two-qubit gates (CZ leakage); measurement errors (Meas.); single-qubit gate error (1Q); data-qubit idle error during measurement and reset of auxiliary qubits (Data idle); reset error (Reset); leakage due to incoherent heating from |1⟩ to |2⟩ (Heating). The relative contributions of the different error channels are indicated.
