Charge dynamics and spin blockade in a hybrid double quantum dot in silicon

Electron spin qubits in silicon, whether in quantum dots or in donor atoms, have long been considered attractive qubits for the implementation of a quantum computer due to the semiconductor vacuum character of silicon and its compatibility with the microelectronics industry. While donor electron spins in silicon provide extremely long coherence times and access to the nuclear spin via the hyperfine interaction, quantum dots have the complementary advantages of fast electrical operations, tunability and scalability. Here we present an approach to a novel hybrid double quantum dot by coupling a donor to a lithographically patterned artificial atom. Using gate-based rf reflectometry, we probe the charge stability of this double quantum dot system and the variation of quantum capacitance at the interdot charge transition. Using microwave spectroscopy, we find a tunnel coupling of 2.7 GHz and characterise the charge dynamics, which reveals a charge T2* of 200 ps and a relaxation time T1 of 100 ns. Additionally, we demonstrate spin blockade at the inderdot transition, opening up the possibility to operate this coupled system as a singlet-triplet qubit or to transfer a coherent spin state between the quantum dot and the donor electron and nucleus.Comment: 6 pages, 4 figures, supplementary information (3 pages, 4 figures

Perfil antropométrico, composición corporal y somatotipo de remeros tradicionales de élite: Estudio transversal

Introduction: Given the importance of body composition in sports performance, it is vital to have references of elite athletes which serve as a guide when it comes to overseeing diet and training.The aim of this study was to describe the anthropometric values of an elite team of traditional rowers in order to build an anthropometric profile in this sport. Material and methods: A cross-sectional design with twenty elite, male traditional rowers aged at 29.3 (3.6) years reported to the laboratory on a single day at the start of the competitive season. Height, wingspan, body mass, 8 skinfolds, 2 bone diameters and 6 perimeters were measured by the same internationally certified anthropometrist. Anthropometric measurements were taken following the International Society of Advancement of Kinanthropometry (ISAK) protocol. Fat mass was calculated using different equations for athletes and muscle mass using the Lee equation. For the somatotype components, the Carter and Heath equation was applied.Results: elite traditional rowers had a wingspan of 189 (5.8) cm, body fat percentage of 8.0 (1.2)% (Carter), 8.0 (1.8) (Withers), 7.0 (1.2)% (Yuhasz), and 10.9 (1.1)% (Faulkner). Muscle mass was 43.3 (2.4)% (Lee). The somatotype was endo-mesomorphic with endomorphy values of 3.5 (0.4), mesomorphy 4.7 (0.6) and ectomorphy 2.4 (3.5).Conclusion: These results suggest that wingspan seems to be of great importance for elite traditional rowers; while average height may not be as important for performance as wingspan. Meanwhile, reducing body fat percentage is likely to be beneficial in order to achieve elite rowing status.Introducción: Debido a la importancia que la composición corporal tiene en el rendimiento deportivo es necesario disponer de referencias de deportistas élite que sirvan de guía a la hora de orientar la dieta y el entrenamiento. Material y métodos: El estudio fue diseñado como un estudio transversal que incluyó a veinte remeros tradicionales de élite de 29,3(3,6) años de edad que acudieron al laboratorio un sólo día al comienzo del período competitivo. La altura, envergadura, masa corporal, 8 pliegues cutáneos, 2 diámetros óseos y 6 perímetros fueron determinados por el mismo antropometrista internacionalmente certificado. Las medidas fueron recogidas siguiendo el protocolo de la Sociedad Internacional para el avance de la Cineantropometría (ISAK). La masa grasa se calculó utilizando diferentes ecuaciones para deportistas, y la masa muscular mediante la ecuación de Lee. Los componentes del somatotipo fueron estimados mediante la ecuación Carter y Heath.Resultados: Se observó que los remeros de elite tenían una envergadura de 189 (5,8) cm, un porcentaje de grasa corporal de 8,0 (1,2)% según las ecuaciones de Carter, 8,0 (1,8) de Withers; 7,0 (1,2)% de Yuhasz, y 10,9 (1,1)% de Faulkner. La masa muscular fue de 43,3 (2,4)% según la ecuación de Lee. El somatotipo fue endo-mesomorfo con valores de endomorfia de 3,5(0,4), mesomorfia de 4,7(0,6) y ectomorfia de 2,4 (3,5). Conclusiones: Estos resultados sugieren que la envergadura parece ser de gran importancia para los remeros de élite, mientras que la altura promedio puede no ser tan importante para el rendimiento. Por su parte, reducir el porcentaje de grasa corporal es probablemente beneficioso para lograr un buen rendimiento en este deporte

Relación de la ingesta a largo plazo de macronutrientes en las hormonas anabólicas-catabólicas de jugadoras de voleibol elite

[EN] Introduction: Specific macronutrient distribution and training can alter acute and chronic hormone behavior and, subsequently, sport performance. Objective: The main aim was to examine relationships between dietary intake and anabolic/catabolic hormone response in elite female volleyball players during a 29-week season. Methods: Twenty-two elite female volleyballers (26.4 ± 5.6 years; 178 ± 9 cm; 67.1±7.5 kg) had dietary intake (seven-day dietary recall and food frequency questionnaire), blood concentration of anabolic/catabolic hormones concentration, physical performance, and body composition assessed at four time points: a) T1: baseline/pre-testing; b) T2: eleven weeks after T1; c) T3: ten weeks after T2; and d) T4: eight weeks after T3. Hormones evaluated were: total testosterone (TT), free testosterone (FT) adrenocorticotropic hormone (ACTH), and cortisol (C), along with hormone ratios. Results: Positive correlations were observed between carbohydrate/protein ratio with ΔFT (r = 0.955; p 0.05) in body mass or body mass index at any time point, and the sum of six skinfolds improved (p < 0.05) from T1 (86.5 ± 6.9 mm) to T4 (75.2 ± 5.6 mm) as did muscle mass (T1: 28.9 ± 0.7 kg vs T4: 30.1 ± 0.8 kg). Vertical jump, spike-jump and speed improved (p < 0.05) from T1 to T4. Conclusions: A high carbohydrate/protein ratio was associated with positive changes in anabolism, while high protein and low carbohydrates (CHO) were associated with an attenuated anabolic response[ES] Introducción: la distribución específica de macronutrientes y el entrenamiento pueden alterar el comportamiento agudo y crónico de las hormonas y, posteriormente, el rendimiento deportivo. Objetivo: el objetivo principal del estudio fue examinar la relación entre la ingesta dietética y la respuesta anabólica/catabólica hormonal de jugadoras de élite de voleibol durante una temporada de 29 semanas. Métodos: se evaluó en 22 jugadoras de élite (26,4 ± 5,6 años, 178 ± 9 cm, 67,1 ± 7,5 kg) la ingesta dietética (mediante un registro de siete días y un cuestionario de frecuencia de consumo de alimentos), la concentración de hormona anabólica/catabólica en sangre, el rendimiento físico y la composición corporal en cuatro puntos durante la temporada: a) T1: pre-pretemporada; b) T2: once semanas después de T1; c) T3: diez semanas después de T2; y d) T4: ocho semanas después de T3. Las hormonas evaluadas fueron: testosterona total (TT), testosterona libre (FT), hormona adrenocorticotropa (ACTH) y cortisol (C); se calcularon distintos ratios hormonales. Resultados: se observaron correlaciones positivas entre la ratio carbohidratos/proteínas con ΔFT (r = 0,955; p 0,05) en la masa corporal ni en el índice de masa corporal en ningún momento, mientras que el sumatorio de seis pliegues mejoró (p < 0,05) de T1 (86,5 ± 6,9 mm) a T4 (75,2 ± 5,6 mm), así como la masa muscular (T1: 28,9 ± 0,7 kg frente a T4: 30,1 ± 0,8 kg). El salto vertical, el salto de remate y la velocidad mejoraron (p < 0,05) de T1 a T4. Conclusión: en conclusión, una alta ratio de carbohidratos/proteínas se asoció con cambios positivos en el anabolismo, mientras que una ingesta alta de proteína y baja de CHO se asoció con una respuesta anabólica atenuada.S

FeCoCp3 Molecular Magnets as Spin Filters

Metallorganic molecules have been proposed as excellent spin filters in molecular spintronics because of the large spin-polarization of their electronic structure. However, most of the studies involving spin transport, have disregarded fundamental aspects such as the magnetic anisotropy of the molecule and the excitation of spin-flip processes during electron transport. Here, we study a molecule containing a Co and an Fe atoms stacked between three cyclopentadienyl rings that presents a large magnetic anisotropy and a S=1. These figures are superior to other molecules with the same transition metal, and improves the spin-filtering capacities of the molecule. Non-equilibrium Green's functions calculations based on density functional theory predict excellent spin-filtering properties both in tunnel and contact transport regimes. However, exciting the first magnetic state drastically reduces the current's spin polarization. Furthermore, a difference of temperature between electrodes leads to strong thermoelectric effects that also suppress spin polarization. Our study shows that in-principle good molecular candidates for spintronics need to be confronted with inelastic and thermoelectric effects

Broadband parametric amplification for multiplexed SiMOS quantum dot signals

Spins in semiconductor quantum dots hold great promise as building blocks of quantum processors. Trapping them in SiMOS transistor-like devices eases future industrial scale fabrication. Among the potentially scalable readout solutions, gate-based dispersive radiofrequency reflectometry only requires the already existing transistor gates to readout a quantum dot state, relieving the need for additional elements. In this effort towards scalability, traveling-wave superconducting parametric amplifiers significantly enhance the readout signal-to-noise ratio (SNR) by reducing the noise below typical cryogenic low-noise amplifiers, while offering a broad amplification band, essential to multiplex the readout of multiple resonators. In this work, we demonstrate a 3GHz gate-based reflectometry readout of electron charge states trapped in quantum dots formed in SiMOS multi-gate devices, with SNR enhanced thanks to a Josephson traveling-wave parametric amplifier (JTWPA). The broad, tunable 2GHz amplification bandwidth combined with more than 10dB ON/OFF SNR improvement of the JTWPA enables frequency and time division multiplexed readout of interdot transitions, and noise performance near the quantum limit. In addition, owing to a design without superconducting loops and with a metallic ground plane, the JTWPA is flux insensitive and shows stable performances up to a magnetic field of 1.2T at the quantum dot device, compatible with standard SiMOS spin qubit experiments

A cost-effective algae-based biosensor for water quality analysis: Development and testing in collaboration with peasant communities

New anthropic potentially harmful compounds are released into the environment everyday. In this context, broad range bioassays have emerged providing economically viable and widely applicable alternatives due to their ability to detect the cumulative toxicity of mixtures of both known and unknown chemicals in a sample, thus allowing direct information about water quality. Here we present a low-cost, wide-range algae-based biosensor that is easy to assemble and operate by untrained users and provides direct readings. It was developed as a request of a peasant social movement organization to assess the toxicity of drinking water in rural communities affected by pesticide spraying. Two fresh water algae strains, Scenedesmus acutus and Pseudokirchneriella subcapitata, were immobilized in alginate beads and tested as bioindicators. After incubation with different pollutants for five days, naked eye analysis by several observers proved to be a successful method to survey algae’s growth and establish the detection limits. Best detection limits were 10 ppm for technical-grade acid glyphosate, 15 ppm for glyphosate-based formulation, 50 ppb for atrazine formulation, 7.5 ppm for copper and 250 ppb for chromium. Absorbance measurements upon algae resuspension validated these results. The developed device was successfully tested in participatory workshops conducted at rural communities. Children, adults and elders with no scientific training were able to build the sensor and interpret the results, thus evaluating the quality of rain and well water used in their communities.Universidad Nacional de Santiago del EsteroConsejo Nacional de Investigaciones Científicas y Técnica

Influencing the properties of dysprosium single-molecule magnets with phosphine, phosphide and phosphinidene ligands

Single-molecule magnets are a type of coordination compound that can retain magnetic information at low temperatures. Single-molecule magnets based on lanthanides have accounted for many important advances, including systems with very large energy barriers to reversal of the magnetization, and a di-terbium complex that displays magnetic hysteresis up to 14 K and shows strong coercivity. Ligand design is crucial for the development of new single-molecule magnets: organometallic chemistry presents possibilities for using unconventional ligands, particularly those with soft donor groups. Here we report dysprosium single-molecule magnets with neutral and anionic phosphorus donor ligands, and show that their properties change dramatically when varying the ligand from phosphine to phosphide to phosphinidene. A phosphide-ligated, trimetallic dysprosium single-molecule magnet relaxes via the second-excited Kramers’ doublet, and, when doped into a diamagnetic matrix at the single-ion level, produces a large energy barrier of 256 cm1 and magnetic hysteresis up to 4.4 K

Anthropometric profile, body composition and somatotype in elite traditional rowers: A cross-sectional study

Introduction: Given the importance of body composition in sports performance, it is vital to have references of elite athletes which serve as a guide when it comes to overseeing diet and training.The aim of this study was to describe the anthropometric values of an elite team of traditional rowers in order to build an anthropometric profile in this sport. Material and methods: A cross-sectional design with twenty elite, male traditional rowers aged at 29.3 (3.6) years reported to the laboratory on a single day at the start of the competitive season. Height, wingspan, body mass, 8 skinfolds, 2 bone diameters and 6 perimeters were measured by the same internationally certified anthropometrist. Anthropometric measurements were taken following the International Society of Advancement of Kinanthropometry (ISAK) protocol. Fat mass was calculated using different equations for athletes and muscle mass using the Lee equation. For the somatotype components, the Carter and Heath equation was applied.Results: elite traditional rowers had a wingspan of 189 (5.8) cm, body fat percentage of 8.0 (1.2)% (Carter), 8.0 (1.8) (Withers), 7.0 (1.2)% (Yuhasz), and 10.9 (1.1)% (Faulkner). Muscle mass was 43.3 (2.4)% (Lee). The somatotype was endo-mesomorphic with endomorphy values of 3.5 (0.4), mesomorphy 4.7 (0.6) and ectomorphy 2.4 (3.5).Conclusion: These results suggest that wingspan seems to be of great importance for elite traditional rowers; while average height may not be as important for performance as wingspan. Meanwhile, reducing body fat percentage is likely to be beneficial in order to achieve elite rowing status.Introducción: Debido a la importancia que la composición corporal tiene en el rendimiento deportivo es necesario disponer de referencias de deportistas élite que sirvan de guía a la hora de orientar la dieta y el entrenamiento. Material y métodos: El estudio fue diseñado como un estudio transversal que incluyó a veinte remeros tradicionales de élite de 29,3(3,6) años de edad que acudieron al laboratorio un sólo día al comienzo del período competitivo. La altura, envergadura, masa corporal, 8 pliegues cutáneos, 2 diámetros óseos y 6 perímetros fueron determinados por el mismo antropometrista internacionalmente certificado. Las medidas fueron recogidas siguiendo el protocolo de la Sociedad Internacional para el avance de la Cineantropometría (ISAK). La masa grasa se calculó utilizando diferentes ecuaciones para deportistas, y la masa muscular mediante la ecuación de Lee. Los componentes del somatotipo fueron estimados mediante la ecuación Carter y Heath.Resultados: Se observó que los remeros de elite tenían una envergadura de 189 (5,8) cm, un porcentaje de grasa corporal de 8,0 (1,2)% según las ecuaciones de Carter, 8,0 (1,8) de Withers; 7,0 (1,2)% de Yuhasz, y 10,9 (1,1)% de Faulkner. La masa muscular fue de 43,3 (2,4)% según la ecuación de Lee. El somatotipo fue endo-mesomorfo con valores de endomorfia de 3,5(0,4), mesomorfia de 4,7(0,6) y ectomorfia de 2,4 (3,5). Conclusiones: Estos resultados sugieren que la envergadura parece ser de gran importancia para los remeros de élite, mientras que la altura promedio puede no ser tan importante para el rendimiento. Por su parte, reducir el porcentaje de grasa corporal es probablemente beneficioso para lograr un buen rendimiento en este deporte