Space quantization (Stern-Gerlach experiment)

What was discovered

A beam of silver atoms passing through a non-uniform magnetic field splits into two discrete beams instead of spreading out: the magnetic moment only takes quantised values. First direct proof of the quantisation of a directional quantity and the basis for spin.

Gerlach carried out the experiment; the result was only correctly interpreted as spin from 1927 onwards.

What it led to

• Electron spin
• Concept of quantum measurement
• Magnetic resonance (Rabi's beam method)
• Spin-based quantum technologies

Built on

• Bohr-Sommerfeld model
• Stern's molecular beam technique

Made possible

• Electron spin1925
• Landau quantization1930
• Nuclear magnetic resonance in condensed matter1946
• Caesium atomic clock1955
• Molecular beams

📄 Original publication

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