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Double slit with electrons
Intermediate
Single electrons build up an interference pattern.
Fire electrons one at a time through two slits: each lands as a single dot, yet over time an interference pattern appears. If you detect which slit, the pattern disappears.
Done with molecules of C₆₀ and larger.
Requires the path to be unknowable.
In more detail
In the electron double-slit experiment, electrons fired one at a time build up an interference pattern, showing that each electron behaves as a wave that passes through both slits.
Real-world uses
- It demonstrates the foundations of quantum mechanics.
- It is used in teaching and in quantum measurement research.
- Teaching labs demonstrate that even one electron at a time forms an interference pattern when it passes through two slits.
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Frequently asked questions
Do electrons pass through both slits?
The wavefunction does, and the pattern shows interference between the two possibilities.
What happens if we detect which slit?
The interference pattern disappears, showing that measurement affects the outcome.
What does the pattern show?
Each electron interferes with itself, so the probability distribution of where it lands shows wave behaviour.
Related topics in Quantum Mechanics
de Broglie hypothesis · Davisson–Germer experiment · Wave–particle duality · Heisenberg uncertainty principle · Energy–time uncertainty · Wavefunction