Suppressing quantum errors by scaling a surface code logical qubit

Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum error correction offers a path to algorithmically-relevant error rates by encoding logical qubits within many physical qubits, where increasing the number of physical qubits enhances protection against physical errors. We report the measurement of logical qubit performance scaling across multiple code sizes, demonstrating that our system of superconducting qubits has sufficient performance to overcome the additional errors from increasing qubit number.