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Glossary

Quantum glossary

Interference

Amplitudes for the same outcome adding up (constructive) or cancelling (destructive).

This, not “trying every answer at once”, is the source of quantum speedups: an algorithm is choreographed so that wrong answers cancel and right answers reinforce before you measure.

See it for yourself

Related terms

  • Amplitude — The complex number attached to each possible outcome of a quantum state; its squared magnitude is that outcome’s probability.
  • Phase — The angle of a complex amplitude; relative phases between outcomes decide how they interfere.
  • Superposition — A quantum state that is a weighted combination of basis states, with complex amplitudes.