Surface code with decoherence: An analysis of three superconducting architectures

We consider realistic, multiparameter error models and investigate the performance of the surface code for three possible fault-tolerant superconducting quantum computer architectures. We map amplitude and phase damping to a diagonal Pauli “depolarization” channel via the Pauli twirl approximation, and obtain the logical error rate as a function of the qubit T1,2 and state preparation, gate, and readout errors. A numerical Monte Carlo simulation is performed to obtain the logical error rates, and a leading-order analytic formula is derived to estimate their behavior below threshold. Our results suggest that scalable fault-tolerant quantum computation should be possible with existing superconducting devices.