Superpositioning of electrons in magnets

1. Nov 17, 2006

davidong3000

I understand that in the bell theorem photonic spin is in a superpoistion state until one observes it. Is that also the case with electrons? If so then how come magnets are magnets? Surely the electrons already made up their minds which way their north and south magnetic poles are pointing according to their spin axis right? Thus generating the magnetic fields in magnets? Then surely they are no longer in superpositioned state? Or are electrons in magnets colapsed wavefunctions and behaving as permenant particles?

Dave

Last edited: Nov 17, 2006
2. Nov 22, 2006

davidong3000

any takers?

3. Nov 22, 2006

lightarrow

I preface that I'm not an expert on this subject.
AFAIK you have a sort of prepared state here, that is, the atoms spins have been magnetically polarized, so they are not in a superposition of states any longer. The analogous with photons would be light that has been polarized.

4. Nov 22, 2006

StatMechGuy

You're talking about a statistical system, so what's relevant isn't the individual quantum states, but the bulk average. In thermal equilibrium, the distributions are very sharply peaked about the averages, so you can regard things as being mostly in an energy eigenstate. However, because we're averaging, it doesn't terribly matter if it's in an energy eigenstate or not.

5. Nov 23, 2006

davidong3000

what is eigenstate?

Dave

6. Nov 23, 2006

Staff Emeritus
Very short description.

An operator O acts on states p to produce other states q. In notation O(p) = q. This is the math description of on observation acting on a setup to produce a result.

Some of the states are special in that when the operator acts on them, it only multiplies them by a number; so O(p) = cp, where c is some constant number. A state with this property is called an eigenstate of the operator, the constant is called an eigenvalue. The set of all the eigenstates of an operator is called the spectrum of that operator.

Last edited: Nov 23, 2006
7. Nov 24, 2006

davidong3000

ok so the electrons in magnets are in superpositioned state but they still average out to point thier poles in the direction of the north and south poles of the magnets?

What happens if we measure the spins of all the electrons in the magnets from an angle that is perpendicular to the magnet's length? Would we not force the poles to change by a 90 degree angle?

Dave