= Poincaré sphere
{c}
{{wiki=Polarization_(waves)#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:
* left/right
* diagonal up/diagonal down
* rotation clockwise/counterclockwise
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 Quantum Mechanics 9b - Photon Spin and Schrodinger's Cat II by ViaScience (2013)>.
\Image[https://upload.wikimedia.org/wikipedia/commons/thumb/a/a7/Poincaresp.png/800px-Poincaresp.png]
{title=Poincare sphere}