title: Assessing the polarization of a quantum field from stokes fluctuations.
abstract: We propose an operational degree of polarization in terms of the variance of the Stokes vector minimized over all the directions of the Poincaré sphere. We examine the properties of this second-order definition and carry out its experimental determination. Quantum states with the same standard (first-order) degree of polarization are correctly discriminated by this new measure. We argue that a comprehensive quantum characterization of polarization properties requires a whole hierarchy of higher-order degrees.
authors.affiliation: Departamento de Física, Universidad de Guadalajara, 44420 Guadalajara, Jalisco, Mexico.
authors.forename: A B
authors.initials: AB
authors.lastname: Klimov
authors.forename: G
authors.initials: G
authors.lastname: Björk
authors.forename: J
authors.initials: J
authors.lastname: Söderholm
authors.forename: L S
authors.initials: LS
authors.lastname: Madsen
authors.forename: M
authors.initials: M
authors.lastname: Lassen
authors.forename: U L
authors.initials: UL
authors.lastname: Andersen
authors.forename: J
authors.initials: J
authors.lastname: Heersink
authors.forename: R
authors.initials: R
authors.lastname: Dong
authors.forename: Ch
authors.initials: Ch
authors.lastname: Marquardt
authors.forename: G
authors.initials: G
authors.lastname: Leuchs
authors.forename: L L
authors.initials: LL
authors.lastname: Sánchez-Soto