First of all, I am a computer science student and I have a question regarding the polarization of light as stated in an article entitled "Multi-stage quantum secure communication using polarization hopping" by Rifai et al.,2015.
Given the Mueller matrix:
The input of light state is...
cos 2χ = ((Eb^2 - (Ea)^2) / ((Eb)^2 + (Ea)^2) = (-2(EL*ER)) / ((EL)^2 + (ER)^2)
sin 2χ = (2Ea*Eb) / ((Eb)^2 + (Ea)^2) = ((ER)^2 - (EL)^2) / ((EL)^2 + (ER)^2)
where EL and ER are the left and right circularly polarized field components of a wave.