Quantum Wave Interference (Double Slit)
Fire photons, electrons or neutrons one at a time and watch the wave pattern build dot by dot.
Fire particles one at a time. Each lands at a single spot, but after thousands they build a wave pattern. Turn on the detector and the pattern disappears.
About the Quantum Wave Interference (Double Slit)
Free quantum wave interference (double slit). Fire photons, electrons or neutrons one at a time and watch the wave pattern build dot by dot. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for atomic & quantum, the quantum wave interference (double slit) runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Fire photons, electrons or neutrons one at a time and watch the wave pattern build dot by dot. Use it to explore atomic & quantum ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Quantum Wave Interference (Double Slit)
- Use the controls to change Particle, Slit separation, Rate, Which-slit detector. The simulation reacts instantly.
- Pick an option such as Photon, Electron, Neutron, Off to switch modes or load an example.
- Press "Clear screen" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Fire 500 photons and see the fringes.
- Turn on the detector.
- Switch to neutrons.
Key ideas you can learn
- Single particles build up an interference pattern.
- Each particle is detected at one place.
- A detector at the slits destroys the pattern.
- Heavier particles have shorter wavelengths.
Where this is used in the real world
Electron microscopes and quantum computing rely on the wave nature of particles.
Who is this simulation for?
Advanced high-school and university students in chemistry and physics, and curious learners who want to see how the atomic world behaves.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
Why does the pattern appear with single particles?
Each particle behaves like a wave that goes through both slits and interferes with itself, but is detected as a single dot.
What happens if you watch which slit?
The interference disappears and you see two blobs.
Is the Quantum Wave Interference (Double Slit) free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Quantum Wave Interference (Double Slit) work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.