Luis Aina, Alfredo2023-06-202023-06-202007-09-051050-294710.1103/PhysRevA.76.035801https://hdl.handle.net/20.500.14352/51491©2007 The American Physical Society. This work has been supported by Project No. PR1-A/07-15378 of the Universidad Complutense. I thank the anonymous referees for comments that have helped me to improve the paper.We examine the relationship between nonseparable transformations and nonlinear optical processes, surpassing the Heisenberg limit in precision measurements.engjournal articlehttp://dx.doi.org/10.1103/PhysRevA.76.035801http://journals.aps.org/open access535Projection noiseStatesÓptica (Física)2209.19 Óptica Física