Maximally polarized states for quantum light fields
Luis Lorenzo Sánchez-Soto, E. C. Yustas, Gunnar G. Bjork, A. B. Klimov · Physical Review A · 2007
The degree of polarization of a quantum field can be defined as its distance to an appropriate set of states. When we take unpolarized states as this reference set, the states optimizing this degree for a fixed average number of photons $\overline{N}$ present a fairly symmetric, parabolic photon statistic, with a variance scaling as ${\overline{N}}^{2}$. Although no standard optical process yields such a statistic, we show that, to an excellent approximation, a highly squeezed vacuum can be taken as maximally polarized. We also consider the distance of a field to the set of its SU(2) transformed, finding that certain linear superpositions of SU(2) coherent states make this degree to be unity.