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Glossary

Quantum glossary

Quantum key distribution

Also: qkd, bb84, e91

Protocols such as BB84 that let two parties agree a secret key, with any eavesdropping revealed by the errors it causes.

Security rests on measurement disturbance and no-cloning rather than a hard maths problem. In practice it needs dedicated optical links, is limited in distance, and still requires an authenticated classical channel.

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Related terms

  • No-cloning theorem — There is no process that makes an independent copy of an arbitrary unknown quantum state.
  • Post-quantum cryptography — Classical cryptography designed to resist attack by quantum computers, running on ordinary hardware.