451 research outputs found

    Deterministic generation of an on-demand Fock state

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    We theoretically study the deterministic generation of photon Fock states on-demand using a protocol based on a Jaynes Cummings quantum random walk which includes damping. We then show how each of the steps of this protocol can be implemented in a low temperature solid-state quantum system with a Nitrogen-Vacancy centre in a nano-diamond coupled to a nearby high-Q optical cavity. By controlling the coupling duration between the NV and the cavity via the application of a time dependent Stark shift, and by increasing the decay rate of the NV via stimulated emission depletion (STED) a Fock state with high photon number can be generated on-demand. Our setup can be integrated on a chip and can be accurately controlled.Comment: 13 pages, 9 figure

    Demonstration of entanglement-by-measurement of solid state qubits

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    Projective measurements are a powerful tool for manipulating quantum states. In particular, a set of qubits can be entangled by measurement of a joint property such as qubit parity. These joint measurements do not require a direct interaction between qubits and therefore provide a unique resource for quantum information processing with well-isolated qubits. Numerous schemes for entanglement-by-measurement of solid-state qubits have been proposed, but the demanding experimental requirements have so far hindered implementations. Here we realize a two-qubit parity measurement on nuclear spins in diamond by exploiting the electron spin of a nitrogen-vacancy center as readout ancilla. The measurement enables us to project the initially uncorrelated nuclear spins into maximally entangled states. By combining this entanglement with high-fidelity single-shot readout we demonstrate the first violation of Bells inequality with solid-state spins. These results open the door to a new class of experiments in which projective measurements are used to create, protect and manipulate entanglement between solid-state qubits.Comment: 6 pages, 4 figure

    Thermal shape fluctuation effects in the description of hot nuclei

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    The behavior of several nuclear properties with temperature is analyzed within the framework of the Finite Temperature Hartree-Fock-Bogoliubov (FTHFB) theory with the Gogny force and large configuration spaces. Thermal shape fluctuations in the quadrupole degree of freedom, around the mean field solution, are taken into account with the Landau prescription. As representative examples the nuclei 164^{164}Er, 152^{152}Dy and 192^{192}Hg are studied. Numerical results for the superfluid to normal and deformed to spherical shape transitions are presented. We found a substantial effect of the fluctuations on the average value of several observables. In particular, we get a decrease in the critical temperature (TcT_c) for the shape transition as compared with the plain FTHFB prediction as well as a washing out of the shape transition signatures. The new values of TcT_c are closer to the ones found in Strutinsky calculations and with the Pairing Plus Quadrupole model Hamiltonian.Comment: 17 pages, 8 Figure

    Clinical factors associated with high glycemic variability defined by coefficient of variation in patients with type 2 diabetes

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    Antecedentes: La Variabilidad Glucémica Alta (VHG) ha convertirse en un predictor más fuerte de hipoglucemia. Sin embargo, aún se desconocen los factores clínicos asociados con el VHG. Objetivo:Determinar las variables clínicas que se asociaron con un coeficiente de variación (CV) superior al 36% evaluado mediante monitorización continua de glucosa (MCG) en un grupo de pacientes con diabetes mellitus. Métodos: Se evaluó una cohorte de pacientes con diabetes tipo 2 (T2D). Se evaluaron variables demográficas, HbA1c, tasa de filtración glomerular (TFG) y régimen de tratamiento. Se realizó un análisis bivariado, para evaluar la asociación entre la variable resultado (CV > 36%) y cada una de las variables independientes. Se construyó un modelo multivariado para evaluar las asociaciones después de controlar las variables de confusión. Resultados:Se analizaron los datos de MCG de 274 pacientes. CV> 36% estuvo presente en 56 pacientes (20,4%). En el análisis bivariado se incluyeron variables demográficas y clínicas, como tiempo desde el diagnóstico, antecedente de hipoglucemia, A1c, FG y tratamiento instaurado. En el análisis multivariante, FG 9% (OR 2,81; IC 1,05,7,51; p:0,04) y antecedentes de hipoglucemia (OR 2,09; IC 1,02, 4,32; p: 0,04) se asociaron con VHG. El tratamiento con iDPP4 (OR 0,39; IC 0,19, 0,82; p: 0,01) y AGLP1 (OR 0,08; IC 0,01, 0,68; p: 0,02) se asoció inversamente con la VG. Conclusión:Variables clínicas como FG 9% y antecedentes de hipoglucemia se asocian a un VG alto. Nuestros datos sugieren que el uso de tecnología y tratamientos capaces de reducir la variabilidad glucémica podría ser útil en esta población para reducir el riesgo de hipoglucemia y mejorar el control glucémico.Q3Background: High glycemic Variability (HGV) has become a stronger predictor of hypoglycemia. However, clinical factors associate with HGV still are unknown. Objective: To determine clinical variables that were associated with a coefficient of variation (CV) above 36% evaluated by continuous glucose monitoring (CGM) in a group of patients with diabetes mellitus. Methods: A cohort of patients with type 2 diabetes (T2D) was evaluated. Demographic variables, HbA1c, glomerular filtration rate (GFR) and treatment regimen were assessed. A bivariate analysis was performed, to evaluate the association between the outcome variable (CV> 36%) and each of the independent variables. A multivariate model was constructed to evaluate associations after controlling for confounding variables. Results: CGM data from 274 patients were analyzed. CV> 36% was present in 56 patients (20.4%). In the bivariate analysis, demographic and clinical variables were included, such as time since diagnosis, hypoglycemia history, A1c, GFR and treatment established. In the multivariate analysis, GFR 9% (OR 2.81; CI 1.05,7.51; p:0.04) and hypoglycemia history (OR 2.09; CI 1.02,4.32; p:0.04) were associated with HGV. Treatment with iDPP4 (OR 0.39; CI 0.19,0.82; p:0.01) and AGLP1 (OR 0.08; CI 0.01,0.68; p:0.02) was inversely associated with GV. Conclusion: Clinical variables such as GFR 9% and a history of hypoglycemia are associated with a high GV. Our data suggest that the use of technology and treatments able to reduce glycemic variability could be useful in this population to reduce the risk of hypoglycemia and to improve glycemic control.Revista Internacional - Indexad

    Efecto de niveles altos de melaza de caña en la alimentación y de su inversión enzimática sobre la actividad de invertasa intestinal en monogástricos

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    Se condujeron dos experimentos con el objeto de obtener información del efecto que niveles elevados de melaza de caña de azúcar en la dieta tienen sobre el comportamiento (ganancia de peso, consumo y conversión de alimento), la consistencia de las heces

    Chapter 13 - Knock, knock-let the bacteria in: enzymatic potential of plant associated bacteria

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    Beneficial bacteria associated with plants have evolved for thousands of years together with their hosts to an intricate communication system that allow the recognition and penetration into plant tissues without harming them. Within the molecules involved in this communication system, the enzymes produced by the bacteria have an important role and some of them have been shown essential at first steps of plant colonization. In this chapter, we analyze the implication of some of the most well-known enzymes related to plant probiotic bacteria and their hosts, the steps at which these enzymes participate to allow the recognition by the plants and the bacterial penetration into their inner tissues. Between these enzymes we will examine the importance of (i) cellulases, produced by important plant growth promoters to penetrate plant tissues; (ii) chitinases, implicated in the defense of the plant against fungi and recognition by the plants; (iii) lectins, implicated in the attachment and first recognition steps; (iv) pectinases, which are usually expressed early during infection, in the penetration steps; and (v) xylanases, implicated in the recycling at senescence, amongst others. The upregulated expression of some of these enzymes in plant growth promoting bacteria was surprising at first, as they would be expected in pathogens, not in mutualistic microorganisms. However, as more data are available, the implication of hydrolytic enzymes in beneficial plant colonization is become clear

    Experimental loophole-free violation of a Bell inequality using entangled electron spins separated by 1.3 km

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    For more than 80 years, the counterintuitive predictions of quantum theory have stimulated debate about the nature of reality. In his seminal work, John Bell proved that no theory of nature that obeys locality and realism can reproduce all the predictions of quantum theory. Bell showed that in any local realist theory the correlations between distant measurements satisfy an inequality and, moreover, that this inequality can be violated according to quantum theory. This provided a recipe for experimental tests of the fundamental principles underlying the laws of nature. In the past decades, numerous ingenious Bell inequality tests have been reported. However, because of experimental limitations, all experiments to date required additional assumptions to obtain a contradiction with local realism, resulting in loopholes. Here we report on a Bell experiment that is free of any such additional assumption and thus directly tests the principles underlying Bell's inequality. We employ an event-ready scheme that enables the generation of high-fidelity entanglement between distant electron spins. Efficient spin readout avoids the fair sampling assumption (detection loophole), while the use of fast random basis selection and readout combined with a spatial separation of 1.3 km ensure the required locality conditions. We perform 245 trials testing the CHSH-Bell inequality S2S \leq 2 and find S=2.42±0.20S = 2.42 \pm 0.20. A null hypothesis test yields a probability of p=0.039p = 0.039 that a local-realist model for space-like separated sites produces data with a violation at least as large as observed, even when allowing for memory in the devices. This result rules out large classes of local realist theories, and paves the way for implementing device-independent quantum-secure communication and randomness certification.Comment: Raw data will be made available after publicatio

    Ultrafast optical control of entanglement between two quantum dot spins

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    The interaction between two quantum bits enables entanglement, the two-particle correlations that are at the heart of quantum information science. In semiconductor quantum dots much work has focused on demonstrating single spin qubit control using optical techniques. However, optical control of entanglement of two spin qubits remains a major challenge for scaling from a single qubit to a full-fledged quantum information platform. Here, we combine advances in vertically-stacked quantum dots with ultrafast laser techniques to achieve optical control of the entangled state of two electron spins. Each electron is in a separate InAs quantum dot, and the spins interact through tunneling, where the tunneling rate determines how rapidly entangling operations can be performed. The two-qubit gate speeds achieved here are over an order of magnitude faster than in other systems. These results demonstrate the viability and advantages of optically controlled quantum dot spins for multi-qubit systems.Comment: 24 pages, 5 figure

    ECOLOGICAL NICHE OF SEMIDOMESTICATED POPULATIONS OF Capsicum pubescens RUIZ & PAV. BASED ON ACCESSIONS FROM VERACRUZ, MEXICO

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    Para cultivar una especie silvestre es necesario modificar el esquema genético resultante de los procesos de selección natural a uno adaptado a las condiciones manejadas por el hombre, e implica detectar áreas geográficas similares a aquellas donde se originó la especie. En este estudio se analiza un modelo de áreas geográficas potenciales para la adaptación de Capsicum pubescens Ruiz & Pav. con el objetivo de detectar las condiciones de nicho ecológico apropiado, determinar zonas potenciales en México y describir las relaciones entre el medio ambiente y las características morfológicas del fruto. Se utilizó el algoritmo reciente de máxima entropía (MaxEnt) para modelar el nicho de C. pubescens dentro de una región de importancia en el centro de Veracruz, México. Se utilizó un total de 44 sitios de presencia y cuatro variables bioclimáticas para detectar nichos adecuados para la especie; así mismo, se realizó un análisis de regresión por mínimos cuadrados parciales (PLS) combinando los sitios de presencia, variables bioclimáticas y características morfológicas del fruto. Se construyó un mapa final de idoneidad identificando las áreas adecuadas para el crecimiento de C. pubescens. Las contribuciones de las variables predictoras al modelo fueron preipitación anual (Bio12) 43.9 %, capa de potasio (K) 23 %, altitud (DEM) 22.3 % y temperatura media anual (Bio1) 10.7 %, con valor del área bajo la curva de 99.7 %. Los mínimos cuadrados parciales corroboraron la importancia de las covariables, que intervienen en la expresión de características morfológicas del fruto, ayudando a entender mejor las relaciones entre especies y el medio ambiente. Áreas aún no exploradas arrojaron probabilidades de ocurrencia mayores a 90 %, principalmente en las zonas montañosas de Chihuahua, Tamaulipas, Nuevo León y la Sierra de Santa Martha al sur del estado de Veracruz. Se identificó un grupo de accesiones sobresalientes que podrían servir como base para iniciar un programa de mejoramiento genético en esta especie
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