Person: Luis Aina, Alfredo
Universidad Complutense de Madrid
Faculty / Institute
Now showing 1 - 10 of 111
- PublicationObserved quantum dynamics: classical dynamics and lack of Zeno effect(IOP Publishing Ltd, 2020-09-18) López, Julián; Ares Santos, Laura; Luis Aina, AlfredoWe examine a case study where classical evolution emerges when observing a quantum evolution. By using a single-mode quantum Kerr evolution interrupted by measurement of the double-homodyne kind (projecting the evolved field state into classical-like coherent states or quantum squeezed states), we show that irrespective of whether the measurement is classical or quantum there is no quantum Zeno effect and the evolution turns out to be classical.
- PublicationNonclassical light revealed by the joint statistics of simultaneous measurements(Optical Society of America, 2016-04-15) Luis Aina, AlfredoNonclassicality cannot be a single-observable property, since the statistics of any quantum observable is compatible with classical physics. We develop a general procedure to reveal nonclassical behavior of light states from the joint statistics arising in the practical measurement of multiple observables. Beside embracing previous approaches, this protocol can disclose nonclassical features for standard examples of classical-like behavior, such as SU(2) and Glauber coherent states. When combined with other criteria, this would imply that every light state is nonclassical.
- PublicationQuantum-classical correspondence for visibility, coherence, and relative phase for multidimensional systems(American Physical Society, 2008-08-08) Luis Aina, AlfredoWe develop a thorough connection between visibility, coherence, and phase statistics for N-dimensional quantum systems and N classical waves.
- PublicationFisher information as a generalized measure of coherence in classical and quantum optics(The Optical Society Of America, 2012-10-22) Luis Aina, AlfredoWe show that metrological resolution in the detection of small phase shifts provides a suitable generalization of the degrees of coherence and polarization. Resolution is estimated via Fisher information. Besides the standard two-beam Gaussian case, this approach provides also good results for multiple field components and nonGaussian statistics. This works equally well in quantum and classical optics.
- PublicationHeisenberg limit for displacements with semiclassical states(American Physical Society, 2004-04-01) Luis Aina, AlfredoWe analyze the quantum limit to the sensitivity of the detection of small displacements. We focus on the case of free particles and harmonic oscillators as the systems experiencing the displacement. We show that the minimum displacement detectable is proportional to the inverse of the square root of the mean value of the energy in the state experiencing the displacement (Heisenberg limit). We present a measuring scheme that reaches this limit using semiclassical states. We examine the performance of this strategy under realistic practical conditions by computing the effect of imperfections such as losses and nonunit detection efficiencies. This analysis confirms the robustness of this measuring strategy by showing that the experimental imperfections can be suitably compensated by increasing the mean energy of the input state.
- PublicationNonclassicality in the statistics of noncommuting observables: Nonclassical states are more compatible than classical states(American Physical Society, 2011-07-08) Luis Aina, AlfredoWe study nonclassicality in the product of the probabilities of noncommuting observables. We show that within the quantum theory, nonclassical states can provide larger probability product than classical states, so that nonclassical states approach the nonfluctuating states of the classical theory more closely than classical states. This is particularized to relevant complementary observables such as conjugate quadratures, phase and number, quadrature and number, and orthogonal angular momentum components.
- PublicationAlternative measures of uncertainty in quantum metrology: contradictions and limits(American Physical Society, 2013-03-07) Luis Aina, Alfredo; Rodil, AlfonsoWe 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 changes of physical quantities. We show that different measures lead to contradictory conclusions, including the possibility of arbitrarily small uncertainty for fixed resources. These intrinsic performances are compared with the averaged error in the corresponding estimation problem after single-shot measurements.
- PublicationOptimum phase-shift estimation and the quantum description of the phase difference(American Physical Society, 1996-11) Luis Aina, Alfredo; Peřina, J.The problem of a correct quantum description of the phase difference is examined from the perspective of parameter estimation theory. It is shown that an optimum phase-shift measurement defines a phase difference operator which coincides with other approaches to the same problem. We also study the fundamental limit to the accuracy of a phase difference shift detection. We show that this limit can be reached by a measurement having countable outcomes despite the fact that a phase shift can take any value. We show that this is the case of the phase difference operator defined by an optimum phase-shift measurement.
- PublicationBeam splitter as quantum coherence-maker(IOP Publishing, 2023-01-01) Ares Santos, Laura; Luis Aina, AlfredoThe aim of this work is to answer the question of how much quantum coherence a beam splitter is able to produce. To this end, we consider as the variables under study both the amount of coherence of the input states as well as the beam splitter characteristics. We conclude that there is an optimal combination of these factors making the gain of coherence maximum. In addition, the two-mode squeezed vacuum arises as the studied state most capable of gaining coherence when passing through a beam splitter. These results are qualitatively equivalent for the l1-norm of coherence and the relative entropy of coherence.