Rivas, ÁngelLuis Aina, Alfredo2023-06-202023-06-202008-10-141050-294710.1103/PhysRevA.78.043814https://hdl.handle.net/20.500.14352/51465©2008 The American Physical Society. A. R. acknowledges financial support from the University of Hertfordshire and the EU Integrated Project QAP. A. L. acknowledges support from Project No. FIS2008-01267/FIS of the Spanish Direccion General de Investigacion del Ministerio de Ciencia e Innovacion.We develop practical schemes for the measurement of the covariance matrix for intrinsic angular-momentum variables in quantum optics. We particularize this approach to two-beam polarimetry and interferometry, as well as to ensembles of two-level atoms interacting with classical fields. We show the practical advantages of noisy simultaneous measurements.engjournal articlehttp://dx.doi.org/10.1103/PhysRevA.78.043814http://journals.aps.org/open access535Homodyne detectionElectromagnetic-fieldsOperational approachConjugate variablesAtom interferometerFringe visibilityLocal oscillatorCoherent statesPhaseEntanglementÓptica (Física)2209.19 Óptica Física