Atomically-thin quantum dots integrated with lithium niobate photonic chips

The electro-optic, acousto-optic and nonlinear properties of lithium niobate make it a highly versatile material platform for integrated quantum photonic circuits. A prerequisite for quantum technology applications is the ability to efficiently integrate single photon sources, and to guide the generated photons through ad-hoc circuits. Here we report the integration of quantum dots in monolayer WSe2 into a Ti in-diffused lithium niobate directional coupler. We investigate the coupling of individual quantum dots to the waveguide mode, their spatial overlap, and the overall efficiency of the hybrid-integrated photonic circuit

Coulomb blockade in an atomically thin quantum dot coupled to a tunable Fermi reservoir

Gate-tunable quantum-mechanical tunnelling of particles between a quantum confined state and a nearby Fermi reservoir of delocalized states has underpinned many advances in spintronics and solid-state quantum optics. The prototypical example is a semiconductor quantum dot separated from a gated contact by a tunnel barrier. This enables Coulomb blockade, the phenomenon whereby electrons or holes can be loaded one-by-one into a quantum dot. Depending on the tunnel-coupling strength, this capability facilitates single spin quantum bits or coherent many-body interactions between the confined spin and the Fermi reservoir. Van der Waals (vdW) heterostructures, in which a wide range of unique atomic layers can easily be combined, offer novel prospects to engineer coherent quantum confined spins, tunnel barriers down to the atomic limit or a Fermi reservoir beyond the conventional flat density of states. However, gate-control of vdW nanostructures at the single particle level is needed to unlock their potential. Here we report Coulomb blockade in a vdW heterostructure consisting of a transition metal dichalcogenide quantum dot coupled to a graphene contact through an atomically thin hexagonal boron nitride (hBN) tunnel barrier. Thanks to a tunable Fermi reservoir, we can deterministically load either a single electron or a single hole into the quantum dot. We observe hybrid excitons, composed of localized quantum dot states and delocalized continuum states, arising from ultra-strong spin-conserving tunnel coupling through the atomically thin tunnel barrier. Probing the charged excitons in applied magnetic fields, we observe large gyromagnetic ratios (~8). Our results establish a foundation for engineering next-generation devices to investigate either novel regimes of Kondo physics or isolated quantum bits in a vdW heterostructure platform.Comment: Published in Nature Nanotechnology. 7 pages + 14 supplementary information pages. 14 figure

Influencia de factores bióticos a escala local y de paisaje en la distribución del muérdago en pinares mediterráneos

The study of the spatial patterns of species allows the examination of hypotheses on the most plausible ecological processes and factors determining their distribution. To investigate the determinants of parasite species on Mediterranean forests at regional scales, occurrence data of the European Misletoe (Viscum album) in Catalonia (NE Iberian Peninsula) were extracted from forest inventory data and combined with different types of explanatory variables by means of generalized linear mixed models. The presence of mistletoes in stands of Pinus halepensis seems to be determined by multiple factors (climatic conditions, and characteristics of the host tree and landscape structure) operating at different spatial scales, with the availability of orchards of Olea europaea in the surroundings playing a relevant role. These results suggest that host quality and landscape structure are important mediators of plant-plant and plant-animal interactions and, therefore, management of mistletoe populations should be conducted at both local (i.e. clearing of infected host trees) and landscape scales (e.g. controlling the availability of nutrient-rich food sources that attract bird dispersers). Research and management at landscape-scales are necessary to anticipate the negative consequence of land-use changes in Mediterranean forests.El estudio de los patrones espaciales de las especies permite examinar hipótesis sobre los procesos ecológicos y factores más plausibles que determinan su distribución. Para investigar los determinantes de una especie parásita en bosques mediterráneos a escala regional, se combinaron datos sobre la presencia de muérdago (Viscum album) en Cataluña (NE de la Península Ibérica) extraídos del inventario forestal con diferentes variables explicativas por medio de modelos mixtos generalizados. La presencia de muérdago en masas de Pinus halepensis parece estar determinada por múltiples factores (condiciones climáticas, características del árbol hospedante, y estructura del paisaje) que operan a diferentes escalas espaciales, jugando los cultivos de Olea europaea un papel relevante. Los resultados sugieren que la calidad de los árboles hospedantes y la estructura del paisaje son importantes mediadores de las interacciones planta-planta y planta- animal y, por tanto, la gestión de las poblaciones de muérdago debería llevarse a cabo tanto a nivel local (es decir, cortando árboles hospedantes infectados) como de paisaje (por ejemplo, controlando la disponibilidad de hábitats ricos en nutrientes que atraen a las aves dispersantes). La investigación y gestión a escala de paisaje son necesarias para prevenir las consecuencias negativas de los cambios de uso del suelo en los bosques mediterráneos

Le défigement linguistique comme recours stylistique, et les écueils traductologiques induits de l’espagnol vers le français

The man\u27s gaze transcends reality to so often cosmetic purposes. Referring to literature, here we will only tackle the part of the narrative creation which are the metaphorical interpretation and its derivatives to linger over this other type of diversion realized by the language de-fossilization in its phraseology and lexical applications, leading to many puns. The translator must accommodate to this sign of discursive freedom of authors, establishing semantic and semiotic relations of collusion between the source language and the target language. This is what we will develop on the basis of about ten illustrations from Hispanic literature. For each case, we will emphasize the intuitive logic of the original find, to propose its transfer in French, pointing that through a translatological "intuitivo-cognitive" posture, the translator can develop his very own creativity, a true wager of literary faithfulness

Evaluación de la eficacia de un programa integral de prevención secundaria de la enfermedad cardiovascular en atención primaria: estudio PREseAP

ObjetivosEvaluar la eficacia de un programa integral de prevención secundaria para reducir la morbimortalidad en los pacientes que han tenido una enfermedad cardiovascular, controlar los factores de riesgo y el cumplimiento de la medicación profiláctica para prevenir recurrencias y mejorar la calidad de vida de los pacientes con enfermedad cardiovascular.DiseñoEnsayo clínico aleatorizado por clusters, abierto, pragmático, en atención primaria.EmplazamientoUn total de 42 centros de salud de 8 comunidades autónomas del Estado español.ParticipantesVarones y mujeres hasta 85 años de edad, diagnosticados de enfermedad coronaria y/o accidente cerebrovascular y/o enfermedad vascular periférica en el último año, y que no presenten una enfermedad grave o terminal.IntervenciónSe aleatorizarán los centros de salud para seguir la atención habitual en los pacientes diagnosticados de enfermedad cardiovascular (grupo control) o para implantar un programa integral de prevención secundaria (grupo intervención).Mediciones principalesAcontecimientos letales atribuibles a enfermedad cardiovascular, acontecimientos no letales atribuibles a enfermedad cardiovascular, acontecimientos letales por cualquier causa y calidad de vida relacionada con la salud (SF-36).ObjectivesTo assess the efficacy of a comprehensive secondary prevention programme to reduce morbidity and mortality in patients who have suffered a cardiovascular (CV) event; to control CV risk factors and prophylactic treatment in order to prevent recurrence; and to improve the quality of life of patients with cardiovascular disease.DesignRandomised, pragmatic, open clinical trial in primary care.SettingA total of 42 primary care centres of 8 different areas in Spain.ParticipantsMen and women below 86 years old, diagnosed with coronary disease and/or stroke and/or peripheral vascular disease in the preceding year, and who have no serious or terminal disease.InterventionPrimary care centres will be randomised to following usual care (control group), or to following a comprehensive programme of secondary prevention (intervention group).Main measurementsCardiovascular fatal events, cardiovascular non-fatal events, total mortality and health-related quality of life (SF-36)

Out-of-plane orientation of luminescent excitons in atomically thin indium selenide flakes

Van der Waals materials offer a wide range of atomic layers with unique properties that can be easily combined to engineer novel electronic and photonic devices. A missing ingredient of the van der Waals platform is a two-dimensional crystal with naturally occurring out-of-plane luminescent dipole orientation. Here we measure the far-field photoluminescence intensity distribution of bulk InSe and two-dimensional InSe, WSe$_2$ and MoSe$_2$. We demonstrate, with the support of ab-initio calculations, that layered InSe flakes sustain luminescent excitons with an intrinsic out-of-plane orientation, in contrast with the in-plane orientation of dipoles we find in two-dimensional WSe$_2$ and MoSe$_2$ at room-temperature. These results, combined with the high tunability of the optical response and outstanding transport properties, position layered InSe as a promising semiconductor for novel optoelectronic devices, in particular for hybrid integrated photonic chips which exploit the out-of-plane dipole orientation.Comment: Published in Nature Communications. 12 pages, 5 figures. Link: https://www.nature.com/articles/s41467-019-11920-

Spin–layer locking of interlayer excitons trapped in moiré potentials

Van der Waals heterostructures offer attractive opportunities to design quantum materials. For instance, transition metal dichalcogenides (TMDs) possess three quantum degrees of freedom: spin, valley index, and layer index. Further, twisted TMD heterobilayers can form moir\'e patterns that modulate the electronic band structure according to atomic registry, leading to spatial confinement of interlayer exciton (IXs). Here we report the observation of spin-layer locking of IXs trapped in moir\'e potentials formed in a heterostructure of bilayer 2H-MoSe$_2$ and monolayer WSe$_2$. The phenomenon of locked electron spin and layer index leads to two quantum-confined IX species with distinct spin-layer-valley configurations. Furthermore, we observe that the atomic registries of the moir\'e trapping sites in the three layers are intrinsically locked together due to the 2H-type stacking characteristic of bilayer TMDs. These results identify the layer index as a useful degree of freedom to engineer tunable few-level quantum systems in two-dimensional heterostructures.Comment: 10 pages, 4 figures. Supplementary Material available at: https://www.dropbox.com/s/8331cfoasdofwkq/Brotons-Gisbert_Suppl_Info.pdf?dl=