If I'm correct,in classical physics we can define completely unpolarised light as light where the vibrations of the electric vector occur equally in all directions simultaneously. But can such a definition apply to single photons and if so are the different vibrations assumed to be in superposition? I'm thinking that a source that produces polarised light can be analysed as being due to photons each one of which is polarised randomly with respect to the other photons. Is that correct and if so does each photon maintain its state of polarisation until measured? Thank you. I have searched this but haven't found the answers.