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An alternative derivation of the Pegg-Barnett phase operator is presented. This approach is based on the properties of the representation in quantum mechanics of a nonlinear nonbijective canonical transformation. It does not use as its starting [...]texto impreso
We examine a family of intrinsic performance measures in terms of probability distributions that generalize Hellinger distance and Fisher information. They are applied to quantum metrology to assess the uncertainty in the detection of minute cha[...]texto impreso
We derive simple practical procedures revealing the quantum behavior of angular momentum variables by the violation of classical upper bounds on the statistics. Data analysis is minimum and definite conclusions are obtained without evaluation of[...]texto impreso
Two examples are presented where the observation of the emission in parametric down-conversion leads to its enhancement instead of its inhibition. The improvement is analyzed in terms of the quantum features of the observation.texto impreso
Any nonclassical effect noticed in measured statistics is usually attributed just to the light state being observed. According to Born's rule, quantum probabilities are given by the overlap between the system state and measurement states in a qu[...]texto impreso
We analyze the performance of nonlinear detection schemes surpassing the Heisenberg limit with semiclassical input states when using realistic detectors having nonunit detection efficiency.texto impreso
We provide a very simple case showing that the weak form of the Heisenberg limit can be beaten while the prior information is improved without bias.texto impreso
The well-known difficulties of defining a phase operator of an oscillator are considered from the point of view of the canonical transformation to action and phase-angle variables. This transformation turns out to be nonbijective, i.e., it is no[...]texto impreso
We elaborate an approach to quantum fluctuations of angular momentum based on the diagonalization of the covariance matrix in two versions: real symmetric and complex Hermitian. At difference with previous approaches this is SU(2) invariant and [...]texto impreso
Bermúdez, A. ; Martín-Delgado Alcántara, Miguel Ángel ; Luis Aina, Alfredo | American Physical Society | 2008-06-11We study a relativistic spin-1/2 fermion subjected to a Dirac oscillator coupling and a constant magnetic field. An interplay between opposed chirality interactions culminates in the appearance of a relativistic quantum phase transition, which c[...]texto impreso
Two complementary observables can be measured simultaneously so that the exact individual distributions can be recovered by a proper data inversion. We apply this program to the paradigmatic example of the Young interferometer from the classical[...]texto impreso
We compare the maximum achievable polarization correlations for classical-like separable states and quantum entangled states. For one-photon systems we find that the maximally entangled states have three times larger correlations than the maximu[...]texto impreso
Geometrical optics can be regarded both as the short-wavelength approximation of the propagation of electromagnetic waves, and as the exact way in which propagate the surfaces of discontinuity of the classical electromagnetic field. In this work[...]texto impreso
Porras, Miguel A. ; Luis Aina, Alfredo ; Gonzalo Fonrodona, Isabel | American Physical Society | 2013-11-04We provide theoretical and experimental evidence of a classical-optics realization of quantum Zeno dynamics. In contrast to other approaches, the classical implementation is extremely simple and adaptable. Frequently monitoring the transverse sp[...]texto impreso
Two-path interference of transversal vectorial waves is embedded within a larger scheme: this is four-path interference between four scalar waves. This comprises previous approaches to coherence between vectorial waves and restores the equivalen[...]
