Person:
Luis Aina, Alfredo

First Name

Alfredo

Last Name

Luis Aina

URI

https://hdl.handle.net/20.500.14352/75157

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Óptica

Area

Optica

Identifiers

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Now showing 1 - 10 of 13

Classical and quantum complementarity
(Physics letters A, 2020) Galazo, Raquel; Bartolomé, Irene; Ares Santos, Laura; Luis Aina, Alfredo
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 and quantum points of view. We show complete parallelism between complementarity in the quantum and classical theories. In both domains, complementarity manifests in a pathological behavior for the inferred joint distribution. (C) 2020 Elsevier B.V. All rights reserved.
Nonclassical joint distributions and Bell measurements
(Physics letters A, 2020) Masa, Elisa; Ares Santos, Laura; Luis Aina, Alfredo
Derivation and experimental violation of Bell-like inequalities involve the measurement of incompatible observables. Simple complementarity forbids the existence of such joint probability distribution. Moreover, the measurement of incompatible observables requires different experimental procedures, which no necessarily must share a common joint statistics. In this work, we avoid these difficulties by proposing a joint simultaneous measurement. We can obtain the exact individual statistics of all the observables involved in the Bell inequalities after a suitable data inversion. A lack of positivity or any other pathology of the so retrieved joint distribution is then a signature of nonclassical behavior.
Quantum conditional probabilities
(Journal of physics A: Mathematical and theoretical, 2022) Pérez, Ignacio; Luis Aina, Alfredo
We investigate the consistency of conditional quantum probabilities. This is whether there is compatibility between the Kolmogorov-Bayes conditional probabilities and the Born rule. We show that they are not compatible in the sense that there are situations where there is no legitimate density matrix that may reproduce the conditional statistics of the other observable via the Born rule. This is to say that the Gleason theorem does not apply to conditional probabilities. Moreover, we show that when this occurs the joint statistics is nonclassical. We show that conditional probabilities are not equivalent to state reduction, so these results do not affect the validity of the Luders expression.
Observed quantum dynamics: classical dynamics and lack of Zeno effect
(Journal of physics A: mathematical and theoretical, 2020) López, Julián; Ares Santos, Laura; Luis Aina, Alfredo
We 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.
Signal estimation and coherence
(Optics letters, 2021) Ares Santos, Laura; Luis Aina, Alfredo
We address the relation between quantum metrological resolution and quantum coherence. We develop a quantum version of the Wiener-Khintchine theorem for a suitable model of a quantum ruler, putting the contributions of the probe and measurement on equal footing. We illustrate this approach with several examples of linear metrology.
Beam splitter as quantum coherence-maker
(Physica scripta, 2023) Ares Santos, Laura; Luis Aina, Alfredo
The 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.
Distance-based approach to quantum coherence and nonclassicality
(Physical review A, 2022) Ares Santos, Laura; Luis Aina, Alfredo
We provide a coherence-based approach to nonclassical behavior by means of distance measures. We develop a quantitative relation between coherence and nonclassicality quantifiers, which establish the nonclassicality as the maximum quantum-coherence achievable. We compute the coherence of several representative examples and discuss whether the theory may be extended to reference observables with continuous spectra.
Phase-space quantum Wiener-Khintchine theorem
(Optics letters, 2022) Álvarez Marcos, Ainara; Luis Aina, Alfredo
We derive a quantum version of the classical-optics Wiener-Khintchine theorem within the framework of detec-tion of phase-space displacements with a suitably designed quantum ruler. A phase-space-based quantum mutual coherence function is introduced that includes the contribu-tion of the detector. We obtain an universal equality linking resolution with coherence. This is illustrated with the case of Gaussian states and number states. (c) 2022 Optica Publishing Group
Number-phase entanglement and Einstein-Podolsky-Rosen steering
(Physical review A, 2020) Fadel, Matteo; Ares Santos, Laura; Luis Aina, Alfredo; He, Qiongyi
We use the uncertainty relation between the operators associated with the total number of particles and with the relative phase of two bosonic modes to construct entanglement and Einstein-Podolsky-Rosen steering criteria. These can be tested experimentally in a variety of systems, such as optical fields, Bose-Einstein condensates, and mechanical oscillators. While known entanglement criteria involving the phase observable typically require us to perform interference measurements by recombining the two systems, our criteria can be tested through local measurements at two spatially distinct positions to investigate the nonlocal nature of quantum correlations. We present simple examples where our criteria are violated and show their robustness to noise. Apart from being useful for state characterization, they might find application in quantum information protocols, for example, based on number-phase teleportation.
Apparatus contribution to observed nonclassicality
(Physical review A, 2020) Luis Aina, Alfredo; Ares Santos, Laura
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 quite symmetrical way. We demonstrate that the nonclassicality of the measurement is a necessary condition to obtain nonclassical statistics. To this end, we present a detector characterization for two-observable joint detection processes based on detector tomography. This is particularized to the most common signatures of nonclassical light.