If ##|\alpha>## is spin up, and ##|\beta>## is spin down. Then if angle between those spins and some other up and down spin is ##\theta##, then(adsbygoogle = window.adsbygoogle || []).push({});

[tex]|\alpha'>=\cos \frac{\theta}{2}|\alpha>+\sin \frac{\theta}{2}|\beta>[/tex]

[tex]|\beta'>=\sin \frac{\theta}{2}|\alpha>-\cos \frac{\theta}{2}|\beta>[/tex]

Why?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Angle between spins

**Physics Forums | Science Articles, Homework Help, Discussion**