From polarization multipoles to higher-order coherences

TL;DR

This paper shows that polarization multipoles, derived from the density matrix, are directly observable through specific intensity measurements, providing a natural framework for analyzing quantum polarization states and higher-order coherences.

Contribution

It introduces a method to unambiguously determine polarization multipoles from intensity moments, advancing the analysis of quantum polarization and higher-order coherences.

Findings

Multipoles are observable quantities in quantum polarization.

Measurement scheme involves waveplates and polarizing beam splitter.

Method applies to general two-mode quantum problems.

Abstract

We demonstrate that the multipoles associated with the density matrix are truly observable quantities that can be unambiguously determined from intensity moments. Given their correct transformation properties, these multipoles are the natural variables to deal with a number of problems in the quantum domain. In the case of polarization, the moments are measured after the light has passed through two quarter-wave plates, one half-wave plate, and a polarizing beam splitter for specific values of the angles of the waveplates. For more general two-mode problems, equivalent measurements can be performed.