Luis Aina, Alfredo2023-06-202023-06-202009-05-281050-294710.1103/PhysRevA.79.053855https://hdl.handle.net/20.500.14352/44646©2009 The American Physical Society. This work was supported by Project No. FIS2008-01267 of the Spanish Direccion General de Investigacion del Ministerio de Ciencia e Innovacion.We develop an approach to coherence between two scalar harmonic light vibrations derived from the ensemble interpretation of statistical optics. Coherence is presented as a statistical variable itself that turns out to be the phase difference between the two vibrations. This provides a natural and simple extension of second-order coherence to cover more complicated situations. This includes in a single formalism both classic and quantum light states, allowing the most accurate interferometric measurements, even if they are incoherent according to the standard second-order approach.engjournal articlehttp://dx.doi.org/10.1103/PhysRevA.79.053855http://journals.aps.org/open access535Vectorial electromagnetic-fieldsMach-zehnder interferometerQuantum-phaseUncertainty relationsCorrelation-matricesOptical-phasePolarizationLocalizationInformationSpaceÓptica (Física)2209.19 Óptica Física