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Glossary

Quantum glossary

Quantum error correction

Also: qec

Encoding quantum information redundantly so errors can be detected and fixed without measuring — and destroying — the data.

Instead of reading qubits, you measure parity checks (stabilisers) that reveal where an error occurred but nothing about the encoded state. A classical decoder then decides the most likely correction.

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Related terms

  • Logical qubit — A qubit encoded redundantly across many physical qubits so that errors can be detected and corrected.
  • Syndrome — The pattern of parity-check results that tells an error-correcting code where an error probably happened.
  • Surface code — A quantum error-correcting code laid out on a 2D grid, needing only nearest-neighbour interactions.
  • Error threshold — The physical error rate below which adding more qubits to an error-correcting code makes logical errors rarer, not more common.