A chiral route to spontaneous entanglement generation

We study the generation of spontaneous entanglement between two qubits chirally coupled to a waveguide. The maximum achievable concurrence is demonstrated to increase by a factor of $4/e \sim 1.5$ as compared to the non-chiral coupling situation. The proposed entanglement scheme is shown to be robust against variation of the qubit properties such as detuning and separation, which are critical in the non-chiral case. This result relaxes the restrictive requirements of the non-chiral situation, paving the way towards a realistic implementation. Our results demonstrate the potential of chiral waveguides for quantum entanglement protocols.Comment: 5 pages + 1 page supplemental, 4 figure

Origins of the Commonwealth of Puerto Rico in the Context of United States Strategic Interests in the Caribbean (1938-1950)

The purpose of this paper is to explore the political and military considerations that provided the frame of reference for the promulgation of the Commonwealth of Puerto Rico in 1952. Since 1492 possession of this island has been coveted by nations with vital interest in the Caribbean region. To the United States, who conquered the island in 1898, Puerto Rico formed the backbone of the defense perimeter for the Panama Canal and adjacent shipping lanes. Experience during World War 11 and the subsequent threat from the Soviet Union reinforced the military value of the island. The importance of the geostrategic location of the island to the United States was the crucial factor that determined the type of political system that substituted fifty years of U.S. colonial rule with a measure of self-government. The leadership of Luis Munoz Marin and the moderate ideology of his Partido Popular Democratico (Popular Democratic Party) proved to be the best vehicle for the implementation of the reforms that would guarantee both the preservation of U.S. sovereignty over Puerto Rico and the improvement of the welfare of the people of the island

Electrically controllable magnetism in twisted bilayer graphene

Twisted graphene bilayers develop highly localised states around AA-stacked regions for small twist angles. We show that interaction effects may induce either an antiferromagnetic (AF) and a ferromagnetic (F) polarization of said regions, depending on the electrical bias between layers. Remarkably, F-polarised AA regions under bias develop spiral magnetic ordering, with a relative $120^\circ$ misalignment between neighbouring regions due to a frustrated antiferromagnetic exchange. This remarkable spiral magnetism emerges naturally without the need of spin-orbit coupling, and competes with the more conventional lattice-antiferromagnetic instability, which interestingly develops at smaller bias under weaker interactions than in monolayer graphene, due to Fermi velocity suppression. This rich and electrically controllable magnetism could turn twisted bilayer graphene into an ideal system to study frustrated magnetism in two dimensions, with interesting potential also for a range of applications.Comment: 7 pages, 3 figures. Minor correction

Harvesting Excitons Through Plasmonic Strong Coupling

Exciton harvesting is demonstrated in an ensemble of quantum emitters coupled to localized surface plasmons. When the interaction between emitters and the dipole mode of a metallic nanosphere reaches the strong coupling regime, the exciton conductance is greatly increased. The spatial map of the conductance matches the plasmon field intensity profile, which indicates that transport properties can be tuned by adequately tailoring the field of the plasmonic resonance. Under strong coupling, we find that pure dephasing can have detrimental or beneficial effects on the conductance, depending on the effective number of participating emitters. Finally, we show that the exciton transport in the strong coupling regime occurs on an ultrafast timescale given by the inverse Rabi splitting ($\sim10~$fs), orders of magnitude faster than transport through direct hopping between the emitters.Comment: 5 pages, 3 figure

Intraspecific variability drives diversity in food webs

Biodiversity theories neglect individual-level variability in ecological interactions even though empirical work has revealed considerable genetic and phenotypic variation among individuals in natural populations. This impedes assessing the impact of individual-level variability on biodiversity in multi-trophic ecosystems. Here we use a density-dependent and individual-based food web model, tested against the largest individual-based food web to date, to show that non-random intraspecific variation in prey selection alters species diversity in food webs. Predators consuming many prey increase diversity by preferentially selecting common prey; predators consuming few prey inhibit diversity by preferentially selecting rare prey, putting them at risk of extinction. Thus species-level patterns cannot be explained by species-level averages, but instead must consider individual-level variation in prey selection. Individual-level variation occurs in many biological and social contexts, suggesting that analyses of individual-level interaction data will be relevant in a wide range of fields

Developing of new technologies driving advances in precision agriculture to optimise inputs and reduce environmental footprint

Avances en el sector de la agrotecnología ofrecen la oportunidad de que los sistemas agroalimentarios contribuyan a conseguir objetivos políticos mundiales como lograr sistemas de carbono neto cero y reducir la huella ambiental mediante la eliminación de emisiones nocivas y el aumento de la biodiversidad. Una serie de sensores puede detectar la salud y el estrés de los cultivos debido a amenazas bióticas y abióticas. La detección precoz permite tomar medidas adecuadas antes de que el rendimiento de los cultivos se vea afectado o la presión de plagas y enfermedades no pueda controlarse sin el uso de pesticidas sintéticos. La tecnología de detección utiliza técnicas de imagen o detección de compuestos volátiles mediante e-nose y diagnóstico molecular en tiempo real, identificando patógenos vegetales recogidos en muestras de aire. Los datos generados por estas tecnologías proporcionan a los agricultores información temporal y espacial. Permite identificar plantas individualmente, incluso desde satélite, lo que posibilita aplicar con precisión fertilizantes y pesticidas, directamente a la planta o a la zona de cultivo afectada con técnicas de pulverización controladas a partir utilizando los datos adquiridos.Technological advances in the agri-tech sector offer the opportunity for food production systems to contribute to achieving global policy aims such as achieving net zero carbon systems and reducing environmental footprint through eliminating harmful emissions and increasing biodiversity. Arange of sensors can detect crop health and stress due to biotic and abiotic threats, often with an early detection which permits appropriate action to be taken before crop yield is affected or pest and disease pressure cannot be controlled without the use of synthetic pesticides. Detection technology uses imaging techniques, often beyond the visible spectrum, detection of volatile compounds using e-nose techniques and real time molecular diagnostic techniques to identify plant pathogens collected in air samples. The data generated by such technologies relies on connectivity of the hardware and subsequent analytical processes to provide growers with temporal and spatial information. It is possible to identify plant locations with great accuracy, even with satellite systems, which permits precision application of crop inputs, such as fertilisers and pesticides, directly to the plant or crop area as required. Spray application techniques can now treat individual plants, both crop and weeds, using data acquired to control the flow to individual nozzles