Rivas, ÁngelLuis Aina, Alfredo2023-06-202023-06-202010-06-300031-900710.1103/PhysRevLett.105.010403https://hdl.handle.net/20.500.14352/44641© 2010. The American Physical Society. A. R. acknowledges Susana F. Huelga for illuminating comments and financial support from the EU Integrated Projects QAP, QESSENCE, and the STREP action CORNER. A. L. acknowledges support from official Spanish projects No. FIS2008-01267 and QUITEMAD S2009-ESP-1594.We examine whether metrological resolution beyond coherent states is a nonclassical effect. We show that this is true for linear detection schemes but false for nonlinear schemes, and propose a very simple experimental setup to test it. We find a nonclassicality criterion derived from quantum Fisher information.engjournal articlehttp://dx.doi.org/10.1103/PhysRevLett.105.010403http://journals.aps.org/open access535Wigner functionPhase measurementsHeisenberg limitDensity-matricesNumberStatesComputationDistanceSpaceÓptica (Física)2209.19 Óptica Física