Fig. 1: Stabilizer circuits on Sycamore.
From: Exponential suppression of bit or phase errors with cyclic error correction
a, Layout of distance-11 repetition code and distance-2 surface code in the Sycamore processor. In the experiment, the two codes use overlapping sets of qubits, which are offset in the figure for clarity. b, Pauli error rates for single-qubit and CZ gates and identification error rates for measurement, each benchmarked in simultaneous operation. c, Circuit schematic for the phase-flip code. Data qubits are randomly initialized into \(|+\rangle \) or \(|-\rangle \), followed by repeated application of XX stabilizer measurements and finally X-basis measurements of the data qubits. Hadamard refers to the Hadamard gate, a quantum operation. d, Illustration of error detection events that occur when a measurement disagrees with the previous round. e, Fraction of measurements (out of 80,000) that detected an error versus measurement round for the d = 11 phase-flip code. The dark line is an average of the individual traces (grey lines) for each of the 10 measure qubits. The first (last) round also uses data qubit initialization (measurement) values to identify detection events.
