  We formulate the classical polarization theory for light by using
entanglement analysis. We demonstrate a route to a systematic and consistent
measure of ordinary light polarization that extends automatically to a new
understanding of the degree of polarization at a point, when a distinct beam
direction is absent. We have drawn on recent work [Qian and Eberly, arXiv
1009.5622] dealing with the conservation of quantum information.

Optics;Quantum Physics