Este trabalho teve como finalidade o desenvolvimento de uma técnica de carga para armadilhas magnéticas-óticas. Nosso objetivo com este desenvolvimento foi aumentar a eficiência do aprisionamento de modo a possibilitar sua utilização como etapa inicial na geração de condensados de Bose-Einstein. Com este intuito utilizamos feixes atômicos desacelerados em substituição a liberação de vapor na câmara da armadilha, desta forma eliminando as limitações no vácuo. O elemento distintivo de nossa técnica se baseou na utilização de um disco opaco. Este possuía a função de gerar uma sombra no laser responsável pela desaceleração dos átomos. Ao projetar esta sombra sobre a região de formação da armadilha evitamos os efeitos destrutivos do laser sobre a mesma. Desta maneira conseguimos aumentar consideravelmente o número de átomos aprisionados excepcionalmente em relação a carga a partir vapor, atingindo um número de 7.108 e densidade de 1010 átomos/cm3 numa situação otimizada / The goal was to learn and to develop efficient techniques to be used for quickly loading magneto optical traps. It may become usefull during the first steps towards producing Bose-Einstein condensates. A few different aproaches were attempted in order to avoid the loading from the surrounding thermal vapor. The key factor was the use of an opaque, disc shapped, laser beam block. It was imprinted onto one facet of an optical glass slab and then imaged into the trapping region producing a dark shadow there. This blackned region was found to eliminate the harmful effects of the near resonant light from the decelerating laser beam, which is able to pump a significant fraction of the captured atoms out of the trap. Therefore, we were able to signicantly improve the overall trapping efficiency and the number of atoms captured from the decelerated atomic beam. In the optimal configuration, we counted 7x108 trapped atoms with number densities as high as 1010 atoms/cm3

Orientador: Flavio Caldas da Cruz / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-04T03:39:23Z (GMT). No. of bitstreams: 1 Diogenes_LucianaClaudiaMartinsFerreira_M.pdf: 1151910 bytes, checksum: 87c3f471eecda5a52fde7a9af20b2de6 (MD5) Previous issue date: 2004 / Resumo: Este trabalho consiste em estudar a fraca transição 1S0 - 3P1 do cálcio em um feixe atômico. Essa transição de intercombinação em 657 nm é promissora para um padrão unificado de comprimento, tempo e frequência. A sua detecção óptica diretamente é dificultada por ser uma transição fraca, i.e, com baixa taxa de espalhamento (g ~2000 s -1 ). Como o cálcio possui uma forte transição ( 1 S0 - 1 P1) que compartilha o mesmo nível fundamental com essa transição fraca, podemos observar que quando dois lasers estão acessando ambas as transições o sinal de fluorescência da transição 1 S0 - 1 P1 sofre uma mudança à medida que o laser em 657 nm aproxima-se da ressonância com a transição 1 S0 - 3 P1. Uma simulação foi realizada visando obter as populações de cada um dos três níveis envolvidos em função da dessintonia e intensidade dos lasers / Abstract: This work consists of a study of the weak 1 S 0 - 3 P 1 calcium transition in an atomic beam. This intercombination transition at 657 nm is a promising unified standard of length, time and frequency. Direct optical detection requires is difficult because it is a weak transition (g ~ 2000 s -1). However since calcium has a strong transition ( 1 S0 - 1 P1) which shares the ground state with this weak transition, we can observe that the fluorescence from the 1 S0 -1 P1 transition is modified when a laser at 657 nm is tuned to resonance with the weak intercombination transition. A simulation was carried out to obtain the populations of these three levels as function of the lasers detuning and intensity / Mestrado / Física Atômica e Molecular / Mestre em Física

Orientador: Luís Eduardo Evangelista de Araujo / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-29T14:34:13Z (GMT). No. of bitstreams: 1 FernandezApolinario_Ulices_D.pdf: 32632596 bytes, checksum: 913293ad92a80bba8b449b4814411610 (MD5) Previous issue date: 2015 / Resumo: Nesta tese, propomos, descrevemos e desenvolvemos um novo mecanismo de clonagem de imagens ópticas baseado no efeito atômico coerente da absorção induzida eletromagneticamente ("EIA"). Estudamos experimentalmente a transferência de uma imagem impressa em um feixe forte de acoplamento para um feixe fraco de prova ressonante em um sistema atômico de rubídio de quatro níveis do tipo N degenerado. Nos experimentos, uma imagem bidimensional correspondente a um padrão de linhas horizontais é aplicada ao feixe de acoplamento e transferida para um feixe de prova, de mesma frequência mas polarização ortogonal ao laser de acoplamento. A clonagem de imagem é estudada em função da potência, dessintonia e grau de coerência espacial do feixe de acoplamento. Nós mostramos experimentalmente que o feixe de prova clonado que carrega a imagem é transmitido sem a difração usual. Apresentamos um modelo teórico, para o caso de um feixe de acoplamento espacialmente coerente, que prevê que as características transversais do feixe de acoplamento são transferidas para o feixe de prova de maneira eficiente, apesar da imagem de controle sofrer distorções devido a difração durante a propagação. De fato, as imagens clonadas podem ser muito melhores do que as imagens de acoplamento originais, com estruturas reduzidas em tamanho por aproximadamente um fator de 2. Experimentalmente, verificamos que quanto menor o grau de coerência da luz, melhor é a imagem clonada quando comparada com a imagem de acoplamento a uma mesma distância de propagação. Uma comparação com outras técnicas de clonagem estudadas na literatura, com luz espacialmente coerente, mostra que o nosso mecanismo apresenta um desempenho similar a elas, com uma transmissão máxima da imagem clonada pelo vapor atômico de aproximadamente 10% / Abstract: In this thesis, we propose, describe and develop a new optical imaging cloning mechanism based on the coherent atomic effect of electromagnetically induced absorption ("EIA"). We experimentally study the transfer of an image imprinted onto a strong coupling beam to a resonant weak probe beam in a rubidium atomic system in a degenerate four-level N configuration. In the experiments, a two-dimensional image corresponding to a pattern of horizontal lines is imprinted onto the coupling beam and transferred to a probe beam of the same frequency, but with orthogonal polarization to the coupling laser. Image cloning is studied as a function of power, detuning and the degree of spatial coherence of the coupling beam. We show experimentally that the cloned probe beam carrying the image is transmitted without the usual diffraction. We present a theoretical model, for the case of a fully spatially-coherent coupling beam, that predicts that the transverse characteristics of the coupling beam are efficiently transferred to the probe beam, in spite of distortions of the control image due to diffraction during propagation. Indeed, the cloned images can be much better than the original images of the coupling beam, with structures reduced in size by approximately a factor of 2. Experimentally, we found that the lower the degree of coherence of the coupling light, the better the cloned image compared to the coupling image for the same propagation distance. A comparison with other cloning techniques studied in the literature, with spatally coherent light, shows that our mechanism has a similar performance, with a maximum cloned image transmission by the atomic vapor of approximately 10% / Doutorado / Física / Doutor em Ciências / 153079/2010 / 0554/15 / CNPQ / Funcamp

O complexo formado pela molécula de tetraciclina com o íon de magnésio é capaz de impedir a replicação do material genético no ribossomo bacteriano, tornando a tetraciclina um excelente antibiótico. Outra aplicação da tetraciclina, ligada ao íon európio, consiste em estimar a concentração de colesterol no sangue a partir das mudanças do espectro de emissão. Tal técnica apresenta uma resposta imediata e confiável, comparada às técnicas atuais. Emgeral, o espectro de absorção e emissão da tetraciclina é bastante sensível aos íons alojados e ao pH do solvente que o conjunto está imerso. Entretanto, o espectro de absorção teórico em solvente foi obtido com simples modelos contínuos que não consideram interações específicas impostas pelo ambiente no líquido, além da escassez de estudos teóricos para os complexos. Nossa proposta é obter o espectro de absorção eletrônica da tetraciclina e dos complexos formados com os íons Mg e Eu. Além disso, analisamos as mudanças de intensidade e deslocamentos dos máximos das bandas nos sistemas mencionados, em função do pH do solvente e do posicionamento do íon, estimando seu correto posicionamento. Realizamos a simulação clássica usando a técnica de Monte Carlo aplicando o potencial de Lennard-Jones mais Coulomb para cada átomo da molécula de tetraciclina e dos complexos em água. O espectro de absorção eletrônica foi obtido a partir da teoria funcional da densidade dependente do tempo considerando diversos modelos para descrição do solvente e do íon. Em geral, obtivemos uma boa descrição qualitativa dos espectros, quando comparado com os resultados experimentais. Os deslocamentos das bandas e mudanças de intensidades foram bem descritos pelos modelos que utilizaram a simulação clássica para gerar as configurações. Porém cada modelo privilegiou uma propriedade de um determinado sistema, tanto para as diferentes formas da tetraciclina quanto para a presença de íons. Palavras-chaves: tetraciclina, magnésio-tetraciclina, európio-tetraciclina, espectro de absorção, teoria do funcional da densidade dependente do tempo, simulação por Monte Carlo / The complex formed by the tetracycline molecule with the magnesium ion is able to avoid the replication of the genetic material in bacterial ribosome, making tetracycline an excellent antibiotic. Another application of tetracycline attached to the europium ion, is to evaluate the concentration of cholesterol in the blood from the changes in the emission spectrum. This technique presents an immediate and reliable response compared to current techniques. In general, the absorption and emission spectrum of tetracycline is sensitive to ions coupled and the pH of the solvent that the complex is immersed. However, the theoretical absorption spectrum in solvent was obtained with simple continuum models that do not consider specific interactions imposed by the liquid environment, and also the lack of theoretical studies for the complexes. Our proposal is to obtain the electronic absorption spectrum of tetracycline and complexes formed with the ions Mg and Eu. In addition, we analyze the changes in intensity and peak shifts of the bands in the systems mentioned as the function of pH of the solvent and the position of the ion, and estimating the correct position of the ion. We performed a simulation using the classical Monte Carlo technique applying the Lennard-Jones plus Coulomb potential for each atom of the molecule tetracycline and complexes in water. The electronic absorption spectrum was obtained with the time dependent density functional theory considering several models to describe the solvent and ion. In general, we obtained a good qualitative description of the spectra when compared to the experimental results. The shift of the bands and intensity changes were well described by the used models on classical simulation. However, each model favored one property of the system, both for the different forms of tetracycline and for the presence of ions. Keywords: tetracycline, magnesium-tetracycline, europium-tetracycline, absorption spectrum, time dependent density functional theory, Monte Carlo simulation

Polyhedral Oligomeric Silsesquioxane (POSS) cages are investigated in terms of their potential to enclose small metal hydrides, with the objective of defining conditions that maximize the number of encapsulated hydrogen atoms. Systems of the form MH2n@Tm, where n = 1-3, m = 8, 10, and M comprises metal atom species of the groups IV, VI, VIII, X, and XII, are studied by methods of ab initio and density functional theory (DFT). The resulting composites are categorized with respect to their structural and energetic features. For MH2@T8, it is found in all cases considered that including MH2 into the POSS cage is an endothermic process. For MH2@T10 and M = Ti, Ru, Os, Pt, inclusion of the MH2 guest into the cage turns out to be exothermic, and also leaves the cage intact. For MH4@Tm, this behavior is only observed for one system, OsH4@T10.

Polyhedral Oligomeric Silsesquioxane (POSS) cages are investigated in terms of their potential to enclose small metal hydrides, with the objective of defining conditions that maximize the number of encapsulated hydrogen atoms. Systems of the form MH2n@Tm, where n = 1-3, m = 8, 10, and M comprises metal atom species of the groups IV, VI, VIII, X, and XII, are studied by methods of ab initio and density functional theory (DFT). The resulting composites are categorized with respect to their structural and energetic features. For MH2@T8, it is found in all cases considered that including MH2 into the POSS cage is an endothermic process. For MH2@T10 and M = Ti, Ru, Os, Pt, inclusion of the MH2 guest into the cage turns out to be exothermic, and also leaves the cage intact. For MH4@Tm, this behavior is only observed for one system, OsH4@T10.

Introducción: El COVID-19 es un virus que no solo afecta la salud física, sino que impacta en la salud psicoemocional y en la vida cotidiana de las personas, alterando las dinámicas familiares, laborales, relacionales, educativas y de aprendizaje, entre muchas otras. Objetivo: En este estudio se buscó determinar las diferencias de género en cuanto a los impactos psicoemocionales y las experiencias relacionadas con la pandemia del COVID-19 en población adulta de la zona metropolitana de Guadalajara, México. Método: Se implementó un estudio cualitativo, con teoría fundamentada en los datos, a través de entrevistas semiestructuradas (diez mujeres y tres hombres) y mediante un muestreo no probabilístico por conveniencia. Resultados: Destaca que la experiencia relacionada con COVID-19 ha generado emociones negativas, conflictos de pareja y malestar asociado a la imposibilidad de realizar actividades recreativas. En el caso de las mujeres se han visto trastocadas sus rutinas y han tenido mayor demanda de cuidado y atención de los hijos (en cuanto a la realización de tareas escolares, el tiempo de convivencia, etc.). En cambio, los hombres muestran mayor preocupación por la dificultad trabajar desde el hogar. Conclusión: La pandemia ha impactado de manera distinta a hombre y mujeres, ante esta nueva realidad es fundamental activar los elementos de soporte que faciliten la externalización de las limitantes de movilidad, del cambio de ritmo de vida, del impacto emocional y de los elementos tensionantes que la experiencia del COVID-19 pudo generar en la población.

<p>This dissertation focuses on emergent geometry from SU(1,1) dynamical symmetry and non-Hermitian physics. While the geometrical approach unifies distinct phenomena in Hermitian and non-Hermitian systems, it also provides distinct means of coherent control of quantum dynamics and simulating exotic spacetimes.</p>

<p>Cuprous oxide (Cu₂O) has recently been proposed as a promising solid-state host for ex-<br> citonic Rydberg states with large principal quantum numbers (n) whose exaggerated wave-<br> function sizes (∝ n²) facilitate gigantic, resonant dipole-dipole (∝ n⁴) and van der Waals<br> (∝ n¹¹) interactions, making them an ideal basis for solid-state Rydberg physics and quan-<br> tum technology. Synthetic, thin-film Cu₂O samples are of particular interest because they<br> can be made defect-free via carefully controlled fabrication and are, in principle, suitable<br> for the observation of extreme single-photon nonlinearities caused by Rydberg blockade. In<br> this work, we present the development of a spectroscopy experiment for characterizing the<br> behavior of Rydberg excitons and use it to study a synthetic thin film of Cu₂O grown on a<br> transparent substrate. We present evidence for the presence of states up to n = 8 and conduct<br> the first temperature-dependent study of Rydberg excitons in a thin film. We also propose<br> a technique for studying Rydberg-Rydberg interactions via the creation of high exciton den-<br> sities and establish a set of rate equations for modeling the processes by which excitons are<br> created, interact with each other, and decay. Finally, we conclude with a discussion of the<br> project’s outlook, as well as what future work will be undertaken to study the interactions<br> between Rydberg excitons and utilize them in scalable, integrable, Rydberg-based quantum<br> devices.<br> </p>

<p>  The adiabatic hyperspherical representation has been applied to study few-body systems in both ultracold atomic physics and low energy nuclear physics, as it is a powerful tool that can be used to solve a variety of few-body Hamiltonian's across a wide range of disciplines in physics. In conjunction with the adiabatic hyperspherical representation, we utilized an explicitly correlated Gaussian basis expansion, different from the traditional hyperspherical harmonic expansion typically used with this method. In atomic physics, we applied this method to study the four-body (e^-e^-e⁺e⁺) coulombic system to study positronium-positronium collisions and to get a theoretical value of the 1<em>s</em>-2<em>s</em> scattering length. This work is published in [Phys. Rev. A 100, 012711 (2019)]. We also looked at few-body physics near the unitary limit, particularly near the <em>s</em>- and <em>p</em>-wave unitary limits where the dominant length scale is the scattering length and scattering volume. On this front, we studied universal physics in this regime for the equal-mass system. This work is published in [Phys. Rev. A 106, 023304 (2022)]. This method was further applied to few-body nuclear physics.</p> <p><br></p> <p>  We treat the three and four neutron scattering problems in the <em>N</em>-body continuum to understand and gain insight into possible few-neutron resonances, most notably whether a four-neutron resonance exists. There have been many conflicting theoretical results on whether a four-neutron resonance exists that stemmed from a recent experiment by Kisimori et al. in 2016 [Phys. Rev. Lett. 116, 052501 (2016)]. To provide further theoretical insight on this problem, we use the adiabatic hyperspherical toolkit to probe the scattering continuum and from the 4<em>n</em> density of states, conclude that there is no 4<em>n</em> resonance state. Our work on this is published in [Phys. Rev. Lett. 125, 052501 (2020)] and [Phys. Rev. C 103, 024004 (2021)]. There are other few-body systems in nuclear physics that are explored in the adiabatic hyperspherical representation, including systems like the triton, helium-3, and helium-4 nuclei to visualize and characterize the different reaction pathways the <em>N</em>-body system can fragment into at a given collision energy.</p>