Poincaré sphere

A more photon-specific version of the Bloch sphere.

In it, each of the six sides has a clear and simple to understand photon polarization state, either of:

The sphere clearly suggests for example that a rotational or diagonal polarizations are the combination of left/right with the correct phase. This is clearly explained at: Video 31. "Quantum Mechanics 9b - Photon Spin and Schrodinger's Cat II by ViaScience (2013)".