Stern-Gerlach experiment

In quantum mechanics, the Stern-Gerlach experiment, named after Otto Stern and Walther Gerlach, is a celebrated experiment in 1920 on deflection of particles, often used to illustrate basic principles of quantum mechanics. It can be used to demonstrate that electrons and atoms have intrinsically quantum properties, that measurement in quantum mechanics affects the particles measured, and that quantum states are necessarily described by complex numbers.

References

• Friedrich, Bretislav and Dudley Herschbach, "Stern and Gerlach: How a Bad Cigar Helped Reorient Atomic Physics". Physics Today, December 2003. Available online at http://www.physicstoday.org/vol-56/iss-12/p53.html.