Skip to main content
Glossary

Quantum glossary

Fault tolerance

Also: fault-tolerant quantum computing, ftqc

Running a quantum computation reliably even though every physical component is faulty, by encoding in error-correcting codes.

The threshold theorem says that if physical error rates are below a threshold, logical error rates can be made arbitrarily small by adding more qubits. Useful algorithms like Shor’s need fault tolerance; today’s devices are only just demonstrating logical qubits.

See it for yourself

Related terms

  • Quantum error correction — Encoding quantum information redundantly so errors can be detected and fixed without measuring — and destroying — the data.
  • Error threshold — The physical error rate below which adding more qubits to an error-correcting code makes logical errors rarer, not more common.
  • Logical qubit — A qubit encoded redundantly across many physical qubits so that errors can be detected and corrected.