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Glossary

Quantum glossary

Wavefunction

Also: ψ, psi

The function ψ(x) giving the amplitude for a particle to be found at each position.

|ψ(x)|² is a probability density. It evolves smoothly by the Schrödinger equation, spreads, reflects and interferes like a wave — but is detected as a single particle at a single point.

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Related terms

  • Schrödinger equation — The equation that governs how a quantum state changes in time.
  • Amplitude — The complex number attached to each possible outcome of a quantum state; its squared magnitude is that outcome’s probability.