But coherency matrix is a 2χ2 matrix, which can be constructed by stokes parameters. The density matrix constructed by stokes vector itself would be a 4χ4 matrix.
ρ=(1 1 0 0)χ(1 1 0 0)
If this 4χ4 matrix is a density matrix, how can I measure the degree of polarization of this...
Is a stokes four-vector like (1 1 0 0) being horizontal polarized vector can be treated as a quantum state? If the answer is yes, this state can be used to construct density matrix?