Quantum simulation of Anderson and Kondo lattices with superconducting qubits

We introduce a mapping between a variety of superconducting circuits and a family of Hamiltonians describing localized magnetic impurities interacting with conduction bands. This includes the Anderson model, the single impurity one- and two-channel Kondo problem, as well as the 1D Kondo lattice. We compare the requirements for performing quantum simulations using the proposed circuits to those of universal quantum computation with superconducting qubits, singling out the specific challenges that will have to be addressed.Comment: Longer versio

Generación de imagen tridimensional de objetos sumergidos en aguas turbias

This article presents the design and implementation of a novel method to generate 3D coordinates from the projection of a laser line over a solid object and the processing of the images obtained during scanning. The result obtained is a 3D model of an isometric view that provides the possibility of being seen from different perspectives under a virtual environment. The methodology is applied in the capture and reconstruction of 3D images of objects submerged in murky waters.Este artículo presenta el diseño e implementación de un novedoso método para generar coordenadas tridimensionales a partir de la proyección de una línea láser sobre un objeto sólido y el procesamiento de las imágenes obtenidas durante el escaneo. El resultado obtenido es un modelo tridimensional de una vista isométrica que brinda la posibilidad de ser visto desde diferentes perspectivas bajo un ambiente virtual. La metodología es aplicada en la captura y reconstrucción de imágenes tridimensionales de objetos sumergidos en aguas turbias

Quantum nanoconstrictions fabricated by cryo-etching in encapsulated graphene

More than a decade after the discovery of graphene, ballistic transport in nanostructures based on this intriguing material still represents a challenging field of research in two-dimensional electronics. The presence of rough edges in nanostructures based on this material prevents the appearance of truly ballistic electron transport as theo\-re\-tically predicted and, therefore, not well-developed plateaus of conductance have been revealed to date. In this work we report on a novel implementation of the cryo-etching method, which enabled us to fabricate graphene nanoconstrictions encapsulated between hexagonal boron nitride thin films with unprecedented control of the structure edges. High quality smooth nanometer-rough edges are characterized by atomic force microscopy and a clear correlation between low roughness and the existence of well-developed quantized conductance steps with the concomitant occurrence of ballistic transport is found at low temperature. In par\-ti\-cu\-lar, we come upon exact 2$e^{2}/h$ quantization steps of conductance at zero magnetic field due to size quantization, as it has been theoretically predicted for truly ballistic electron transport through graphene nanoconstrictions

Un caso potencial de depredación de puercoespín (Coendou sp.) por Ocelote (Leopardus pardalis) en La Reserva Natural La Mesenia-Paramillo, Jardín, Antioquia

Here we document evidence of the possible consumption of a porcupine (Coendou sp.) By an Ocelot in a montane forest southwest of Antioquia, Colombia. This represents a remarkable record regarding a new food item (Coendou sp.) In the Ocelot diet in high mountain areas in Colombia. The location of the records is located at 2,100 meters above sea level in the Western Cordillera, in the Natural Reserve La MeseniaParamillo, in the municipality of Jardín, southwest of AntioquiaAquí documentamos evidencia del posible consumo de un puercoespín (Coendou sp.) por un Ocelote en un bosque montano al suroeste de Antioquia, Colombia. Esto representa un registro notable en cuanto a un nuevo ítem alimentario (Coendou sp.) en la dieta del Ocelote en zonas de alta montaña en Colombia. La localidad de los registros está ubicada a 2.100 msnm en la Cordillera Occidental, en la Reserva Natural La MeseniaParamillo, del municipio de Jardín, al suroeste de Antioqui

Butane Dry Reforming Catalyzed by Cobalt Oxide Supported on Ti2AlC MAX Phase

MAX (M(n+1)AX(n)) phases are layered carbides or nitrides with a high thermal and mechanical bulk stability. Recently, it was shown that their surface structure can be modified to form a thin non-stoichiometric oxide layer, which can catalyze the oxidative dehydrogenation of butane. Here, the use of a Ti2AlC MAX phase as a support for cobalt oxide was explored for the dry reforming of butane with CO2, comparing this new catalyst to more traditional materials. The catalyst was active and selective to synthesis gas. Although the surface structure changed during the reaction, the activity remained stable. Under the same conditions, a titania-supported cobalt oxide catalyst gave low activity and stability due to the agglomeration of cobalt oxide particles. The Co3O4/Al(2)O(3)catalyst was active, but the acidic surface led to a faster deactivation. The less acidic surface of the Ti2AlC was better at inhibiting coke formation. Thanks to their thermal stability and acid-base properties, MAX phases are promising supports for CO(2)conversion reactions

Genetic structure, relationships and admixture with wild relatives in native pig breeds from Iberia and its islands

Articles in International JournalsBackground: Native pig breeds in the Iberian Peninsula are broadly classified as belonging to either the Celtic or the Mediterranean breed groups, but there are other local populations that do not fit into any of these groups. Most of the native pig breeds in Iberia are in danger of extinction, and the assessment of their genetic diversity and population structure, relationships and possible admixture between breeds, and the appraisal of conservation alternatives are crucial to adopt appropriate management strategies. Methods: A panel of 24 microsatellite markers was used to genotype 844 animals representing the 17 most important native swine breeds and wild populations existing in Portugal and Spain and various statistical tools were applied to analyze the results. Results: Genetic diversity was high in the breeds studied, with an overall mean of 13.6 alleles per locus and an average expected heterozygosity of 0.80. Signs of genetic bottlenecks were observed in breeds with a small census size, and population substructure was present in some of the breeds with larger census sizes. Variability among breeds accounted for about 20% of the total genetic diversity, and was explained mostly by differences among the Celtic, Mediterranean and Basque breed groups, rather than by differences between domestic and wild pigs. Breeds clustered closely according to group, and proximity was detected between wild pigs and the Mediterranean cluster of breeds. Most breeds had their own structure and identity, with very little evidence of admixture, except for the Retinto and Entrepelado varieties of the Mediterranean group, which are very similar. Genetic influence of the identified breed clusters extends beyond the specific geographical areas across borders throughout the Iberian Peninsula, with a very sharp transition from one breed group to another. Analysis of conservation priorities confirms that the ranking of a breed for conservation depends on the emphasis placed on its contribution to the betweenand within-breed components of genetic diversity. Conclusions: Native pig breeds in Iberia reveal high levels of genetic diversity, a solid breed structure and a clear organization in well-defined clusters

Matter wave pulses characteristics

We study the properties of quantum single-particle wave pulses created by sharp-edged or apodized shutters with single or periodic openings. In particular, we examine the visibility of diffraction fringes depending on evolution time and temperature; the purity of the state depending on the opening-time window; the accuracy of a simplified description which uses ``source'' boundary conditions instead of solving an initial value problem; and the effects of apodization on the energy width.Comment: 11 pages, 11 figure

Discovery of Colossal Breathing-Caloric Effect under Low Applied Pressure in the Hybrid Organic–Inorganic MIL-53(Al) Material

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] In this work, “breathing-caloric” effect is introduced as a new term to define very large thermal changes that arise from the combination of structural changes and gas adsorption processes occurring during breathing transitions. In regard to cooling and heating applications, this innovative caloric effect appears under very low working pressures and in a wide operating temperature range. This phenomenon, whose origin is analyzed in depth, is observed and reported here for the first time in the porous hybrid organic–inorganic MIL-53(Al) material. This MOF compound exhibits colossal thermal changes of ΔS ∼ 311 J K–1 kg–1 and ΔH ∼ 93 kJ kg–1 at room temperature (298 K) and under only 16 bar, pressure which is similar to that of common gas refrigerants at the same operating temperature (for instance, p(CO2) ∼ 64 bar and p(R134a) ∼ 6 bar) and noticeably lower than p > 1000 bar of most solid barocaloric materials. Furthermore, MIL-53(Al) can operate in a very wide temperature range from 333 K down to 254 K, matching the operating requirements of most HVAC systems. Therefore, these findings offer new eco-friendly alternatives to the current refrigeration systems that can be easily adapted to existing technologies and open the door to the innovation of future cooling systems yet to be developed.This work was financially supported by Ministerio de Economía y Competitividad MINECO and EU-FEDER (projects MAT2017-86453-R and PDC2021-121076-I00), Xunta de Galicia and IACOBUS Programme. Funding for open access fee was provided by Universidade da Coruña/CISU

Global ecosystem thresholds driven by aridity

Aridity, which is increasing worldwide because of climate change, affects the structure and functioning of dryland ecosystems. Whether aridification leads to gradual (versus abrupt) and systemic (versus specific) ecosystem changes is largely unknown. We investigated how 20 structural and functional ecosystem attributes respond to aridity in global drylands. Aridification led to systemic and abrupt changes in multiple ecosystem attributes. These changes occurred sequentially in three phases characterized by abrupt decays in plant productivity, soil fertility, and plant cover and richness at aridity values of 0.54, 0.7, and 0.8, respectively. More than 20% of the terrestrial surface will cross one or several of these thresholds by 2100, which calls for immediate actions to minimize the negative impacts of aridification on essential ecosystem services for the more than 2 billion people living in drylands.This research was supported by the European Research Council [ERC grant nos. 242658 (BIOCOM) and 647038 (BIODESERT) awarded to F.T.M.]. M.B. acknowledges support from a Juan de la Cierva Formación grant from the Spanish Ministry of Economy and Competitiveness (FJCI-2018-036520-I). F.T.M. acknowledges support from Generalitat Valenciana (CIDEGENT/2018/041), the Alexander von Humboldt Foundation, and the Synthesis Centre for Biodiversity Sciences (sDiv) of the German Centre for Integrative Biodiversity Research (iDiv). M.D.-B. acknowledges support from the Marie Sklodowska-Curie Actions of the Horizon 2020 Framework Program H2020-MSCA-IF-2016 under REA grant no. 702057. S.S. was supported by the Spanish Government under a Ramón y Cajal contract (RYC-2016- 20604). N.G. was supported by the AgreenSkills+ fellowship program, which has received funding from the EU’s Seventh Framework Programme under grant no. FP7-609398 (AgreenSkills+ contract). V.M. was supported by FRQNT-2017-NC-198009 and NSERC Discovery 2016-05716 grants from the government of Canada. H.S. was supported by a Juan de la Cierva Formación grant from the Spanish Ministry of Economy and Competitiveness (FJCI-2015-26782). A.L. and M.C.R. were supported by an ERC Advanced Grant (Gradual Change grant no. 694368) and by the Deutsche Forschungsgesellschaft (grant no. RI 1815/16-1). Y.Z. was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDA19030500)

Molybdenum Oxide Supported on Ti3AlC2 is an Active Reverse Water−Gas Shift Catalyst

MAX phases are layered ternary carbides or nitrides that are attractive for catalysis applications due to their unusual set of properties. They show high thermal stability like ceramics, but they are also tough, ductile, and good conductors of heat and electricity like metals. Here, we study the potential of the Ti(3)AlC(2 )MAX phase as a support for molybdenum oxide for the reverse water-gas shift (RWGS) reaction, comparing this new catalyst to more traditional materials. The catalyst showed higher turnover frequency values than MoO3/TiO2 and MoO3/Al2O3 catalysts, due to the outstanding electronic properties of the Ti3AlC2 support. We observed a charge transfer effect from the electronically rich Ti3AlC2 MAX phase to the catalyst surface, which in turn enhances the reducibility of MoO3 species during reaction. The redox properties of the MoO3/Ti3AlC2 catalyst improve its RWGS intrinsic activity compared to TiO2- and Al2O3-based catalysts