L: Wave AND Particle Duality: Coherences AND polarizations

The wave-particle duality concept is at the heart of the foundations of quantum mechanics.  Here I want to show that the 2D spin gives a clear visualization that the wave-particle question comes down to how we look at spins.  That is, the wave or particle nature depends upon how we set up the experiment.

This is old hat, of course, going back to the Einstein-Bohr debates, but the 2D spin gives a different perspective.

The question comes down to this: “wave or particle”, or, “wave and particle”. The most widely accepted version is the “or” group which includes the Copenhagen Interpretation (CI).  But this is what bothered EPR, who claimed that quantum mechanics does not live up to a physical theory because QM cannot describe both position and momentum, and likewise two orthogonal axes of angular momentum. Recall that the 2D spin has two orthogonal angular momentum axes and so both cannot be measured simultaneously: in other words the 2D spin must satisfy the Heisenberg Uncertainty relations.