Quantum Measurement: Stern-Gerlach Experiment
Send spin particles through analyzers along Z and X and see how measurement changes the state.
Send spin-½ particles through analyzers. Choose the direction (Z or X) for each analyzer. Measuring along X scrambles what you learned about Z.
About the Quantum Measurement: Stern-Gerlach Experiment
Free quantum measurement: stern-gerlach experiment. Send spin particles through analyzers along Z and X and see how measurement changes the state. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for atomic & quantum, the quantum measurement: stern-gerlach experiment 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.
Send spin particles through analyzers along Z and X and see how measurement changes the state. 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 Measurement: Stern-Gerlach Experiment
- Use the controls to change Analyzer 1, Analyzer 2, Analyzer 3. The simulation reacts instantly.
- Pick an option such as Z, X, off to switch modes or load an example.
- Press "Fire 200 particles", "Clear counts" 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
- Set Z then Z and check results agree.
- Set Z, X, Z and see 50/50.
- Fire many particles.
Key ideas you can learn
- Spin can be measured up or down along any direction.
- Measuring along the same direction again gives the same answer.
- Measuring along a different direction gives 50/50.
- Measurement changes the quantum state.
Where this is used in the real world
Spin measurements are the basis of MRI, quantum computing and magnetic storage.
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
What is the Stern-Gerlach experiment?
An experiment that splits a beam of particles by their spin using a magnetic field.
Why does Z, X, Z give random results?
The X measurement destroys the earlier Z information.
Is the Quantum Measurement: Stern-Gerlach Experiment 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 Measurement: Stern-Gerlach Experiment 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.