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Any practical realization of entanglement-based quantum communication must be intrinsically secure and able to span long distances avoiding the need of a straight line between the communicating parties. The violation of Bell’s inequality offers a method for the certification of quantum links without knowing the inner workings of the devices. Energy-time entanglement quantum communication satisfies all these requirements. However, currently there is a fundamental obstacle with the standard configuration adopted: an intrinsic geometrical loophole that can be exploited to break the security of the communication, in addition to other loopholes. Here we show the first experimental Bell violation with energy-time entanglement distributed over 1 km of optical fibres that is free of this geometrical loophole. This is achieved by adopting a new experimental design, and by using an actively stabilized fibre-based long interferometer. Our results represent an important step towards long-distance secure quantum communication in optical fibres. Practical implementations of quantum communication need to securely deliver information over long distances without line-of-sight. Towards this goal, Cuevas et al. use an actively stabilized interferometer to close the geometry loophole for a Bell inequality violation over 1 km of optical fibre.

A Bell test is a randomized trial that compares experimental observations against the philosophical worldview of local realism 1 , in which the properties of the physical world are independent of our observation of them and no signal travels faster than light. A Bell test requires spatially distributed entanglement, fast and high-efficiency detection and unpredictable measurement settings 2 , 3 . Although technology can satisfy the first two of these requirements 4 – 7 , the use of physical devices to choose settings in a Bell test involves making assumptions about the physics that one aims to test. Bell himself noted this weakness in using physical setting choices and argued that human ‘free will’ could be used rigorously to ensure unpredictability in Bell tests 8 . Here we report a set of local-realism tests using human choices, which avoids assumptions about predictability in physics. We recruited about 100,000 human participants to play an online video game that incentivizes fast, sustained input of unpredictable selections and illustrates Bell-test methodology 9 . The participants generated 97,347,490 binary choices, which were directed via a scalable web platform to 12 laboratories on five continents, where 13 experiments tested local realism using photons 5 , 6 , single atoms 7 , atomic ensembles 10 and superconducting devices 11 . Over a 12-hour period on 30 November 2016, participants worldwide provided a sustained data flow of over 1,000 bits per second to the experiments, which used different human-generated data to choose each measurement setting. The observed correlations strongly contradict local realism and other realistic positions in bipartite and tripartite 12 scenarios. Project outcomes include closing the ‘freedom-of-choice loophole’ (the possibility that the setting choices are influenced by ‘hidden variables’ to correlate with the particle properties 13 ), the utilization of video-game methods 14 for rapid collection of human-generated randomness, and the use of networking techniques for global participation in experimental science. The BIG Bell Test, which used an online video game with 100,000 participants worldwide to provide random bits to 13 quantum physics experiments, contradicts the Einstein–Podolsky–Rosen worldview of local realism.

A Bell test is a randomized trial that compares experimental observations against the philosophical worldview of local realism. A Bell test requires spatially distributed entanglement, fast and high-efficiency detection and unpredictable measurement settings. Although technology can satisfy the first two of these requirements, the use of physical devices to choose settings in a Bell test involves making assumptions about the physics that one aims to test. Bell himself noted this weakness in using physical setting choices and argued that human `free will' could be used rigorously to ensure unpredictability in Bell tests. Here we report a set of local-realism tests using human choices, which avoids assumptions about predictability in physics. We recruited about 100,000 human participants to play an online video game that incentivizes fast, sustained input of unpredictable selections and illustrates Bell-test methodology. The participants generated 97,347,490 binary choices, which were directed via a scalable web platform to 12 laboratories on five continents, where 13 experiments tested local realism using photons, single atoms, atomic ensembles, and superconducting devices. Over a 12-hour period on 30 November 2016, participants worldwide provided a sustained data flow of over 1,000 bits per second to the experiments, which used different human-generated data to choose each measurement setting. The observed correlations strongly contradict local realism and other realistic positions in bipartite and tripartite scenarios. Project outcomes include closing the `freedom-of-choice loophole' (the possibility that the setting choices are influenced by `hidden variables' to correlate with the particle properties), the utilization of video-game methods for rapid collection of human generated randomness, and the use of networking techniques for global participation in experimental science.

Any practical realization of entanglement-based quantum communication must be intrinsically secure and able to span long distances avoiding the need of a straight line between the communicating parties. The violation of Bell's inequality offers a method for the certification of quantum links without knowing the inner workings of the devices. Energy-time entanglement quantum communication satisfies all these requirements. However, currently there is a fundamental obstacle with the standard configuration adopted: an intrinsic geometrical loophole that can be exploited to break the security of the communication, in addition to other loopholes. Here we show the first experimental Bell violation with energy-time entanglement distributed over 1 km of optical fibers that is free of this geometrical loophole. This is achieved by adopting a new experimental design, and by using an actively stabilized fiber-based long interferometer. Our results represent an important step towards long-distance secure quantum communication in optical fibers.

Research using wild animals has diverse aims, such as conservation, environmental management, and the generation of knowledge. The aim of the Institutional Animal Care and Use Committees (IACUCs) is to assure that such research is carried out under high bioethical and animal welfare standards, minimizing animal suffering and environmental impact. This manuscript highlights the relevance of IACUCs as an ally to adjust the procedures on animals to the norm and thus facilitate scientific progress.

La investigación con fauna silvestre tiene diversos propósitos como la conservación de especies, gestión ambiental y generación de conocimiento. El objetivo de los Comités Institucionales de Cuidado y Uso de Animales (CICUAs) es que dicha investigación se realice con altos estándares de bioética y bienestar animal, minimizando el sufrimiento animal y el impacto ambiental. Este articulo destaca la importancia de los CICUAs como un aliado para adecuar los procedimientos con animales a la normativa y facilitar el avance científico.

Daily particle samples were collected in Chillán, Chile, at six urban locations from September 1, 2001, through September 30, 2003. Aerosol samples were collected using monitors equipped with a Sierra Andersen 246-b cyclone inlet on Teflon filters. Average concentrations of coarse particulate matter (PM 10 ) for the 2001-2003 period ranged from 43.4 μg/m 3 to 81.8 μg/m 3 across the six sites. Annual PM 10 concentration levels exceeded the European Union concentration limits. Mean PM 10 levels during the cold season (April through September) were more than twice as high as those observed in the warm season (October through March). Average contributions to PM 10 from organic matter, soil dust, nitrate (NO 3 − ), elemental carbon, ammonium (NH 4 + ), and sulfate (SO 4 2− ) were 31%, 27%, 11%, 8%, 7%, and 5%, respectively. The chemical analyses indicated that carbonaceous substances were the most abundant components of PM 10 in cold months, whereas crustal material was the most abundant component of PM 10 during warm months. Higher concentration levels were observed in the downtown area suggesting a clear anthropogenic origin, whereas in the rural sites the source was mainly natural, such as resuspended soil dust associated with traffic on unpaved roads and agricultural activities.

Fugitive dust emissions from soil are thought to constitute a large fraction of the PM10 and PM2.5 inventory in California's San Joaquin Valley (SJV) and other western air basins, especially during dry periods. The major sources of these emissions are paved and unpaved roads, construction sites, windblown dust, and agricultural activities. Furthermore, PM10 and PM2.5 are considered to be among the most harmful of all air pollutants. When inhaled these particles evade natural defenses of the respiratory system and lodge deep in the lungs causing serious health problems. Some heavy metals in small particles have the tendency to donate electrons and to form basic oxides. Biologically, many metals are essential to living systems and are involved in a variety of cellular, physiological, and structural functions. But at high doses, many metals become toxic. The route of exposure may affect the dose and the site where the metal concentrates, and thus the observed toxic effect. In California’s San Joaquin Valley, agricultural operations are highly complex and potentially significant sources of PM10 and PM2.5, especially during late summer and fall. A series of experiments was conducted to measure PM10 and PM2.5 emissions with traditional array sampling from agricultural operations in San Joaquin Valley. The elemental analysis of PM10 and PM2.5 collected in the field samples was conducted using Proton Induced X-Ray Emissions (PIXE), Proton Elastic Scattering Analysis (PESA) and X-Ray Fluorescence (XRF) analytical techniques available in our laboratory. The composition of PM10 dust collected downwind of agricultural operations is different from the composition of the PM2.5 dust collected at the same time. The smaller particles are enriched in sulphur and in heavy metals.

Transportation is widely recognized to be a significant and increasing source of air pollution. In the city of Chillán there are many public cars, buses and trucks that have been retired from circulation in the metropolitan region (capital city of Santiago) due to strict regulation from local environmental authorities. In order to study air pollution in Chillán, a typical semi-agricultural central valley city located in the southern Bio-Bio Region of Chile, an aerosol monitoring study was established to measure ambient aerosol composition. The contributions of private cars, public cars, buses and delivery trucks were examined at a sampling site located downtown. The aerosol monitor was operated from September 2001 to September 2002. The study employed an IMPROVE PM10 sampler with Anderson inlet at 3 meters above ground collecting PM10 on Teflon membrane filter, nylon and quartz filter. Sulfate concentrations were lower than soil, nitrate, elemental and organic carbon, which contributed significantly to PM10 mass. Soil accounted for 25% of the PM10 mass and carbon particles accounted for just over 50%. Transportation sources appear to be primary sources of the carbon and soil particles. The remaining mass was mostly secondary ammonium nitrate and ammonium sulfate. Some metals, such as V, Ni, Br, and Pb, were measured frequently at the downtown site. They did not contribute appreciably to the PM10 mass, but underscore the importance of transportation sources to measured particulate matter.