Apparatus contribution to observed nonclassicality

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

Nonclassical joint distributions and Bell measurements

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

Beam splitter as quantum coherence-maker

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

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

Inequalities for complementarity in observed statistics

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

A pan-European epidemiological study reveals honey bee colony survival depends on beekeeper education and disease control

Reports of honey bee population decline has spurred many national efforts to understand the extent of the problem and to identify causative or associated factors. However, our collective understanding of the factors has been hampered by a lack of joined up trans-national effort. Moreover, the impacts of beekeeper knowledge and beekeeping management practices have often been overlooked, despite honey bees being a managed pollinator. Here, we established a standardised active monitoring network for 5 798 apiaries over two consecutive years to quantify honey bee colony mortality across 17 European countries. Our data demonstrate that overwinter losses ranged between 2% and 32%, and that high summer losses were likely to follow high winter losses. Multivariate Poisson regression models revealed that hobbyist beekeepers with small apiaries and little experience in beekeeping had double the winter mortality rate when compared to professional beekeepers. Furthermore, honey bees kept by professional beekeepers never showed signs of disease, unlike apiaries from hobbyist beekeepers that had symptoms of bacterial infection and heavy Varroa infestation. Our data highlight beekeeper background and apicultural practices as major drivers of honey bee colony losses. The benefits of conducting trans-national monitoring schemes and improving beekeeper training are discussed

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Diseño y elaboración de un Theremin

El objetivo de este trabajo es explicar de forma clara y sencilla el funcionamiento de un Theremin. Con intención de situarlo en el contexto musical,en el primer capítulo se hará un breve repaso de los fundamentos del sonido y la percepción auditiva. Describiremos en primer lugar cómo distingue el o do sonidos diferentes. También analizaremos cómo los distintos tipos de instrumentos generan el sonido, distinguiendo entre los instrumentos cuyos fundamentos son puramente mecánicos, como pueda ser un tambor, de aquellos que generan el sonido basándose en principios electromagnéticos, siendo el Theremin el mejor ejemplo de estos últimos. A continuación explicamos con más detalle uno de los elementos del diseño, las válvulas de vacío, puesto que no han sido estudiados con detalle durante el Grado, pero tienen una física muy intuitiva detrás de su operativa. Estudiaremos también los circuitos oscilantes LC y cómo, uniendo ambos elementos, podemos formar osciladores básicos en el funcionamiento del Theremin propiamente dicho. En el ultimo apartado describiremos brevemente como se han puesto en práctica los fundamentos anteriormente citados en la construcción de un Theremin, y caracterizaremos su sonido final.Grado en Físic

Signal estimation and coherence

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