Quantum error correction below the surface code threshold
Google's Willow superconducting processor result, reported as a distance-7 surface code memory whose logical error rate falls as the code distance grows, placing the device below the surface code threshold. Scaling from distance-3 to distance-5 to distance-7 patches roughly halves the logical error rate at each step. No abstract was supplied here, so details beyond the headline claim of sub-threshold operation should be checked against the paper.
Why it matters: Sub-threshold operation is the precondition for error-corrected scaling, so this marks the point where adding physical qubits starts buying logical reliability rather than just noise.
Error correction & fault toleranceHardware: superconductingapplied