Person:
Ares Santos, Laura

First Name

Laura

Last Name

Ares Santos

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Óptica

Identifiers

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Now showing 1 - 10 of 11

Observed quantum dynamics: classical dynamics and lack of Zeno effect
(IOP Publishing Ltd, 2020-09-18) 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.
Beam splitter as quantum coherence-maker
(IOP Publishing, 2023-01-01) 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
(Amer Physical Soc, 2022-07-11) 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.
Nonclassical joint distributions and Bell measurements
(Elsevier, 2020-07-16) 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.
Classical and quantum complementarity
(Elsevier, 2020-11-06) 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.
Phase space quantum-classical hybrid model
(Academic Press Inc Elsevier Science, 2019-12) García Moreno, Gerardo; Ares Santos, Laura; Luis Aina, Alfredo
In this work we provide a complete model of semiclassical theories by including back-reaction and correlation into the picture. We specially aim at the interaction between light and a two-level atom, and we also illustrate it via the coupling of two harmonic oscillators. Quantum and classical systems are treated on the same grounds via the Wigner-Weyl phase-space correspondence of the quantum theory. We show that this model provides a suitable mixture of the quantum and classical degrees of freedom, including the fact that the evolution transfers nonclassical features to the classical subsystem and nonquantum behaviour to the quantum subsystem. In that sense, we can no longer distinguish between classical and quantum variables and we need to talk about a hybrid model. (C) 2019 Elsevier Inc. All rights reserved.
Number-phase entanglement and Einstein-Podolsky-Rosen steering
(American Physical Society, 2020-05-22) 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
(Amer Physical Soc, 2020-08-21) 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.
Signal estimation and coherence
(Optical Society of America, 2021-10-26) 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.
Inequalities for complementarity in observed statistics
(Elsevier, 2021-12-29) Masa, Elisa; Ares Santos, Laura; Luis Aina, Alfredo
We provide an analysis of complementarity via a suitably designed classical model that leads to a set of inequalities that can be tested by means of unsharp measurements. We show that, if the measured statistics does not fulfill the inequalities it is equivalent to the lack of a joint distribution for the incompatible observables. This is illustrated by path-interference duality in a Young interferometer. (C) 2021 The Authors. Published by Elsevier B.V.