How do you rotate an electron 360 degrees?

I went through an undergraduate physics program and I've internalized the results of the Stern–Gerlach experiment to the point where it makes more sense to me than the classical version.



However, one thing I somehow missed (or maybe it wasn't taught) is what "must rotate an electron 720 degrees to return it to its original state" actually means. Its not like you can just pick it up and spin it. Do you just make a series of spin measurements at regularly spaced angles?



I would really appreciate a description of or link to an experiment that shows the effect of the negative sign added to an electron's wavefunction after a 360 degree rotation.



thanks,



Dustin Soodak