Classical Circular Polarization vs. Photon Spin Eigenstates

[LarryS]

Hello,

Given an electromagnetic wave that is, from a classical point-of-view, not circular polarized. Does that correspond in QM to photons with the ZERO spin eigenstate?

Thanks in advance.

 

[Orodruin]

Photons do not have a spin 0 eigenstate, since they are massless spin 1 particles. Also be very careful in trying to treat classical fields as photons. Classical fields are generally described by coherent quantum states and not states carrying a particular number of photons.

 

[Avodyne]

No, it corresponds to a superposition of states with spin +1 and -1, just like the classical wave can be written as a superposition (sum) of circularly polarized waves.

 

[LarryS]

So, by "spin +1" and "-1", are you referring to 2 of the 3 eigenvalues of the spin 1 operator/matrix for the Z direction?

 

[Orodruin]

This is the thing, a massless spin 1 particle has only 2 eigenstates.

 

[LarryS]

I just got it. Thank you both.