Fidelity Threshold of the Surface Code Beyond Single-Qubit Error Models

Understand

The surface code is one the most promising alternatives for implementing fault-tolerant, large-scale quantum information processing.

• Its high threshold for single-qubit errors under stochastic noise is one of its most attrative features.
• We develop an exact formulation for the fidelity of the surface code that allows us to probe much further on this promise of strong protection.
• This formulation goes beyond the stochastic single-qubit error model approximation and can take into account both correlated errors and inhomogeneities in the coupling between physical qubits and the environment.