9 research outputs found

    The Quantum Geometric Tensor in a Parameter Dependent Curved Space

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    We introduce a quantum geometric tensor in a curved space with a parameter-dependent metric, which contains the quantum metric tensor as the symmetric part and the Berry curvature corresponding to the antisymmetric part. This parameter-dependent metric modifies the usual inner product, which induces modifications in the quantum metric tensor and Berry curvature by adding terms proportional to the derivatives with respect to the parameters of the determinant of the metric. The quantum metric tensor is obtained in two ways: By using the definition of the infinitesimal distance between two states in the parameter-dependent curved space and via the fidelity susceptibility approach. The usual Berry connection acquires an additional term with which the curved inner product converts the Berry connection into an object that transforms as a connection and density of weight one. Finally, we provide three examples in one dimension with a nontrivial metric: an anharmonic oscillator, a Morse-like potential, and a generalized anharmonic oscillator; and one in two dimensions: the coupled anharmonic oscillator in a curved space.Comment: 22 pages, 6 figure

    Texture characterization of dry-cured ham using multi energy X-ray analysis

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    [EN] Multi energy X-ray sensors are able to differentiate and quantify X-rays of different energies. In contrast to conventional sensors, which simply record the overall energy of the X-rays whatever the energy of x-rays is, multi energy sensors provides a spectrum of the X-rays energies, which may be differently attenuated. In this study, the feasibility of this technology to detect changes in dry-cured ham slices after inducing proteolysis was evaluated. Effect of salt and water contents on the attenuation was also studied. In addition, the classification of commercial samples according to their proteolysis index was assessed. Results showed a decrease of attenuation for increasing proteolysis induction times (p < 0.01) for all the regions of the spectrum (energy bands), but not with the same intensity, at any of the analysed acquisition conditions. Salt and water contents produced a significant (p < 0.01) effect on the attenuation. Influence of salt content was higher than that of water content, and both affected the prediction of the proteolysis index. Classification score of commercial samples exhibited a limited discrimination capacity, showing the need for more sophisticated data analysis. (C) 2018 Elsevier Ltd. All rights reserved.This work was partially supported by INIA (contract n. RTA201300030-0O3-01), Ministerio de Economia y Competitividad (PEJ2014-A34573) and CERCA programme from Generalitat de Catalunya.Fulladosa, E.; Austrich, A.; Muñoz, I.; Guerrero, L.; Benedito Fort, JJ.; Lorenzo, J.; Gou, P. (2018). Texture characterization of dry-cured ham using multi energy X-ray analysis. Food Control. 89:46-53. https://doi.org/10.1016/j.foodcont.2018.01.020S46538

    Cerambyx cerdo L., ¿vulnerable o plaga?

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    Cerambyx cerdo es un coleóptero saproxílico que vive a expensas de Quercus ilex y Quercus suber. Los signos y síntomas visibles que les ocasiona son la acumulación de serrín en la base del tronco, marchitamiento de las ramas terminales y orificios de salida de unos 20 mm de diámetro. Se trata de un insecto amparado por varias figuras protectoras (considerada especie vulnerable según la UICN) debido a la disminución de sus poblaciones al norte de Europa y, por lo tanto, se tienen que priorizar estrategias de conservación en estas áreas. El problema recae en la Región Mediterránea donde representa una amenaza debido a factores bióticos y abióticos, siendo la Isla de Mallorca un claro ejemplo. El objetivo del trabajo es analizar esta situación en Europa y evaluar los métodos de control más adecuados para las zonas del sur debido a su incidencia en los bosques de esclerófilas mediterráneas. A pesar de que el estado de protección en los países del norte es el adecuado, en la Región Mediterránea se tendría que rebajar el grado de protección de la especie y, como medida de control, se recomienda realizar capturas masivas mediante trampas con atrayentes específicos colocadas en troncos de gran diámetro y orientadas al sur o al oeste

    The Quantum Geometric Tensor in a Parameter-Dependent Curved Space

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    We introduce a quantum geometric tensor in a curved space with a parameter-dependent metric, which contains the quantum metric tensor as the symmetric part and the Berry curvature corresponding to the antisymmetric part. This parameter-dependent metric modifies the usual inner product, which induces modifications in the quantum metric tensor and Berry curvature by adding terms proportional to the derivatives with respect to the parameters of the determinant of the metric. The quantum metric tensor is obtained in two ways: By using the definition of the infinitesimal distance between two states in the parameter-dependent curved space and via the fidelity susceptibility approach. The usual Berry connection acquires an additional term with which the curved inner product converts the Berry connection into an object that transforms as a connection and density of weight one. Finally, we provide three examples in one dimension with a nontrivial metric: an anharmonic oscillator, a Morse-like potential, and a generalized anharmonic oscillator; and one in two dimensions: the coupled anharmonic oscillator in a curved space

    Normal modes of vibration of carbon nanotubes doped with nitrogen: towards conducting properties

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    The conducting properties of carbon nanotubes can be changed by nitrogen doping. There exists an enormous interest in modifying the conducting properties of organic and inorganic single and multiwall nanotubes, through doping, since their modified transport properties can be exploited in electronic nano-devices such as diodes, transistors, etc. In this work we study the normal modes of vibration of the armchair (4,4) nanotube: pristine and with nitrogen doping. We used the Density Functional Theory approach including periodic boundary conditions to obtain the ab initio Hessian tensor

    Quantum geometry of the parameter space: a proposal for curved systems

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    In this paper, we extend the quantum geometric tensor for parameter-dependent curved spaces to higher dimensions, and introduce an equivalent definition that generalizes the Zanardi, et al, formulation of the tensor. The parameter-dependent metric modifies the behavior of both the quantum metric tensor and Berry curvature in a purely geometric way. Our focus is on understanding the distinctions in higher dimensions that emerge when using the generalized tensor compared to the conventional one. Through a comparative analysis, illustrated with examples in two dimensions, we highlight unique quantum geometric properties for both the quantum metric tensor and the Berry curvature. Additionally, we explore differences between analytical and perturbative approaches in solving the problems.Comment: 21 page
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