Figure 5
Example of checks that detect all errors. The upper bound on fidelity is saturated at four layers for this randomly generated Clifford input circuit consisting of two qubits and 30 cnot gates. We use depolarizing noise for the given noise model in Fig. 4a. The two-qubit error rate is ten times the single-qubit error rate. The single qubit-error rate ranges from \(10^{-5}\) to \(10^{-1}\). At \(10^{-1}\), each cnot gate (acting on the compute qubits only) is followed by a two-qubit maximal depolarizing channel. Regardless, the postselected state is noiseless, as predicted by Theorem 1.
