# Can a single photon be polarized non-linearly?

I want to check if I correctly understand polarization.

Considering a single photon travelling in vacuum, it can only be polarized linearly under the same direction at any time, right?

When we talk about circular polarization, or unpolarized light, we are talking about sums of linearly polarized photons, with their electric fields ranging from $0$ to $\pi/2$ phase difference?

Actually you can argue that circular polarization is the "more natural" basis for a single photon. The photon carries one unit $\hbar$ of angular momentum, and circularly polarized light carries real angular momentum (an opportunity for me to mention one of my favorite experiments ever, using photon polarization to drive a pendulum).