(a) Determine a 2×2 matrix S that can be used to transform a column vector representing a photon polarization state using the linear polarization vectors ∣x⟩ and ∣y⟩ as a basis to one using the circular polarization vectors ∣R⟩ and ∣L⟩ as a basis.
(b) Using matrix multiplication, verify explicitly that the matrix S that you found in (a) is unitary.