xii, 133 p. : ill. (some col.) / We study entanglement estimation and verification in realistic situations, taking into account experimental imperfections and statistical fluctuations due to finite data. We consider both photonic and spin-1/2 systems. We study how entanglement created with mixed photon wave packets is degraded. We apply statistical analysis to and propose criteria for reliable entanglement verification and estimation. Finally we devote some effort to making quantum state estimation efficient by applying information criteria. This dissertation includes previously published co-authored material. / Committee in charge: Michael G. Raymer, Chair; Steven J. van Enk, Advisor; Stephen Hs,u Member; Jens U. Noeckel, Member; Je rey A. Cina, Outside Member;

xvii, 110 p. : ill. (some col.) / Electron spin states in semiconductors feature long coherence lifetimes, which have stimulated intense interest in the use of these spins for applications in spin based electronics and quantum information processing (QIP). A principal requirement for these spins to be viable candidates in QIP is the ability to coherently control the spins on timescales much faster than the decoherence times. The ability to optically control the spin state can meet this requirement. The spin states of electrons exhibit strong radiative coupling to negatively charged exciton (trion) states, and this radiative coupling makes coherent optical control of spin states possible. This dissertation presents experimental demonstration of coherent control of an electron spin ensemble in a two-dimensional electron gas in a CdTe quantum well. We present two complimentary techniques to optically manipulate these electron spins using a Raman transition. The first demonstration is with a single off-resonant ultrafast optical pulse. This ultrafast pulse acts like an effective magnetic field in the propagation direction of the optical pulse. The second experiment utilizes phase-locked Raman resonant pulse pairs to coherently rotate the quantum state, where the relative phase of the pulse pair sets the axis of rotation. The Raman pulse pair acts like a microwave field driving the spin states. This research demonstrates two significant contributions to the field of coherent optical interactions with semiconductors. First, we have advanced the potential use of electron spin ensembles in semiconductors for optics based quantum information processing hardware through our demonstration of coherent spin flips and complete coherent control. Second, we have experimentally realized full coherent control through the use of phase-locked Raman pulse pairs that overcomes inherent limitations of the single-pulse optical rotation technique, which is the current standard technique used in coherent control. This dissertation includes previously published and unpublished co-authored material. / Committee in charge: Dr. Miriam Deutsch, Chairperson; Dr. Hailin Wang, Advisor; Dr. Steven van Enk, Member; Dr. Raghuveer Parthasarathy, Member; Dr. Catherine Page, Outside Member

No description available.

Apresentamos, nesta tese, uma investigação sobre a estabilização ontológica do fóton, um actante inicialmente articulado no contexto da primeira revolução da Física Quântica. Partindo dos Estudos da Ciência de Bruno Latour, entendemos a ciência como uma rede que se estende por diferentes setores da sociedade e que, portanto, lida com diferentes gêneros do discurso. Além de identificar a importância do gênero científico (artigos seminais) no processo de autonomização dos fatos científicos, também reconhecemos que, na comunidade da Física, os livros didáticos, ou manuais de instrução, tem papel crucial no estabelecimento dos problemas exemplares bem como das teorias hegemônicas, tanto que, hoje, é possível um físico se formar sem estudar os artigos originais sobre Física Quântica. Ademais, os livros didáticos de ciências da Educação Básica são, atualmente, responsáveis pela extensão da rede científica para além dos laboratórios, autonomizando actantes como o fóton em esferas mais amplas da sociedade, papel que Latour poderia chamar de representação pública. O objetivo desta pesquisa é investigar a interação entres esses três gêneros do discurso (artigos seminais, livros didáticos de ensino superior e livros didáticos de ensino médio) e interpretar como que a estabilização ontológica do fóton é mediada por cada um deles. Ao fazer isso, estamos estendendo o programa de pesquisa de Latour em, pelo menos, três sentidos. Primeiramente, incluímos o papel do contexto didático na rede da ciência. Segundo, nossos objetos de investigação estão separados por um intervalo temporal maior do que o usual (aproximadamente cem anos). E, por fim, enquanto Latour dedica-se, principalmente, ao estudo de ciências empíricas, nosso trabalho volta-se para assim chamada Física Teórica, levantando questões ontológicas não discutidas originalmente por Latour. Para dar conta dessa extensão, o presente trabalho está dividido em duas partes. A parte I (Referencial Teórico) traz três artigos sobre as ideias de Bruno Latour e as possibilidades de sua aplicação na pesquisa em Educação em Ciências, o que temos chamado de Sociologia Simétrica da Educação em Ciências ou Estudos da Educação em Ciência. A parte II (Estudos Empíricos) traz quatro artigos (dois sobre as relações entre artigos seminais e livros de ensino superior e dois sobre as relações entre artigos seminais, livros de ensino superior e livros de ensino médio). O primeiro estudo empírico traz uma análise metalinguística do artigo original de Einstein de 1905 em que o quantum é articulado pela primeira vez sem que se precisasse recorrer a nenhum laboratório. No segundo artigo, apresentamos uma análise conceitual e matemática dos artigos de de Broglie e usamos as ideias de Latour para discutir o papel dos livros didáticos na autonomização de sua teoria. No terceiro artigo, analisamos visões epistemológicas em livros didáticos de Física aprovados no Plano Nacional do Livro Didático do Ensino Médio de 2015. E, no quarto artigo, discutimos a narrativa sobre o fóton nesses livros a partir de uma articulação teórica entre ideias de Latour e Bakhtin. Nossos principais resultados apontam o papel articulador da matemática na estabilização de actantes físicos e o papel ativo dos autores de livros didáticos na estabilização do fóton a partir da hibridização de diferentes visões e do uso de mecanismos de causação reversa. / We present an investigation about the ontological stabilization of photon, an actant articulated initially in the context of the first Quantum Revolution. Departing from Bruno Latour’s Science Studies, we take Science as a network spread through different sectors of society and which deals with different speech genders. Besides of identifying the importance of the scientific gender (scientific papers) in the process of autonomation of scientific facts, we also recognize that, in the Physics community, textbooks play a crucial role in the establishment of traditional problems as well as hegemonic theories. Nowadays, someone can conclude an undergraduate course on Physics without having read any of the original papers about Quantum Physics. Furthermore, textbooks in Basic Education are responsible by the extension of the scientific network beyond laboratories, autotomizing actants like the photon in wider spheres of society, what Latour would call public representation. The goal of this research is to investigate the interaction among these three speech genders (original papers, undergraduate textbooks and high school textbooks) and to interpret how the ontological stabilization of photon is mediated by each of them. By doing so, we are extending Latour’s research program in at least three ways. First, we include the didactic context in the science network. Second, our objects of investigation are separated in time by a greater gap (about a hundred years). And third, while Latour studied chiefly the empirical sciences, our work is directed towards the Theoretical Physics, raising ontological questions that were not discussed by Latour. To allow this extension, the work is divided in two parts. Part I (Theoretical Framework) presents three papers about Bruno Latour’s ideas and the possibilities of their application in the research on Science Education, what we have called The Symmetric Sociology of Science Education. Part II (Empirical Studies) presents four papers (two about the relation between original papers and undergraduate textbooks and two about the relation between original papers and high school textbooks). The first empirical study presents a metalinguistic analysis of 1905 Einstein’s paper in which the quantum is articulated by the first time without requiring any laboratory trial. In the second paper, we present a conceptual and mathematical analysis of de Broglie’s papers and we use Latour’s ideas to discuss the role of textbooks in the atomization of his theory. In the third paper, we analyze the epistemological visions present in the Physics textbooks approved by the 2015 National Plan of Textbook. In the fourth paper, we discuss the narrative about the photon present in these books departing from a theoretical articulation between Latour’s and Bakhtin’s ideas. Our chief results point to the articulating role of mathematics in the stabilization of physical actants and the active role of textbooks authors in the stabilization of photon through the hybridization of different visions and the use of the mechanisms of reverse causation.

In this thesis, energy levels, lifetimes, oscillator strengths and transition probabilities of Mg VII have been calculated. The Hartree-Fock (HF) and Multiconfiguration Hartree-Fock (MCHF) methods were used in the calculations of these atomic properties. We have included relativistic operators mass correction, spin-orbit interaction, one body Darwin term and spin-other-orbit interaction in the Breit-Pauli Hamiltonian. The configurations, (1s2)2s22p2, 2s2p3,2p4, 2s22p3s, 2s22p3p,2s2p2(4P)3s and 2s22p3d which correspond to 52 fine-structure levels, were included in the atomic model for the Mg VII ions. The present results have been compared with NIST compilation and other theoretical results, and generally a good agreement was found.

Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / The classical physical science distinguishes itself as a previous project, consisting of the fundamental concepts of elements such as calculation, time, space, motion, matter, force and directed to capture all the nature phenomena supposedly unified. Quantum mechanics advances beyond these postulates, evidencing the inevitable interference of the subject in the search results , in which a reference to an ontological theory with material objects should be able to capture for regularities calculation, it becomes impossible, leaving the core concepts and field for the previous innovative project. As a result, the uncertainty principle that is expressed in a state of motion is identified only as to the statistical calculation or position, or the magnitude of the movement. After the development the existential concept of science that emphasizes the being-there as being-in-the-world to find certain beings as objects by the previous project of the scientific perspective, Heidegger subsequently comes to the conclusion that quantum physics incorporating the classical physics keeps unchangeable in terms of the previous science project of all: the nature disposes in advance a way of securing the meeting proposed by the existing human scientific achievement in theory terms . Science is only an access way to nature in its inexhaustible plenitude, so that it makes it unavoidable and unattainable with the scientificity resources. The com-position is the essence of the technique using scientific results and, by its vortex, enabling it to the final co-existing human. It remains to the being-there the mercy of a thought as to question the destitute condition of his own danger in forgetting that the cooption may be victim of their own decision. / A física clássica distingue-se como ciência por um projeto prévio, composto pelos conceitos fundamentais de elementos como cálculo, tempo, espaço, movimento, matéria, força e direcionado a captar todos os fenômenos da natureza supostamente unificada. A mecânica quântica avança além desses postulados, evidenciando a inevitável interferência do sujeito nos resultados de sua pesquisa, em que a referência a uma teoria ontológica com objetos materiais, devendo ser captáveis para fins de cálculo de regularidades, tornase impossível, restando os conceitos de núcleo e campo para o projeto prévio inovador. Em decorrência, o princípio de incerteza se expressa em que um estado de movimento se identifica somente quanto à calculabilidade estatística ou da posição, ou da grandeza do movimento. Após a elaboração do conceito existencial de ciência, que ressalta o seraí como ser-no-mundo a encontrar entes determinados como objetos pelo projeto prévio da perspectiva científica, Heidegger posteriormente chega à conclusão de que a física quântica incorporando a física clássica permanece imutável no que concerne ao projeto prévio da ciência de sempre: a natureza se dispõe de antemão a um encontro ao modo de asseguramento proposto pelo existente humano numa realização científica em termos de teoria. A ciência permanece apenas como um dos modos de acesso à natureza em sua plenitude inesgotável, o que faz com que ela seja incontornável e inacessível com os recursos da cientificidade. A com-posição é a essência da técnica utilizando resultados científicos e, pela sua voragem, habilitando-se para a cooptação definitiva do existente humano. Resta ao ser-aí a piedade de um pensamento indigente enquanto questionar a sua própria condição de perigo no esquecimento da cooptação de que pode ser vítima por própria decisão.

Apresenta-se um estudo preliminar a respeito das possíveis representações sociais da Física Quântica entre estudantes de diferentes grupos sociais. Após levantamento prévio sobre associações possíveis para a expressão "Física Quântica", foi elaborado um questionário composto por um teste de associação escrita de conceitos (TAEC) e um teste de associação numérica de conceitos (TANC). Responderam ao questionário 494 pessoas, divididas em três grupos: graduandos no curso de Física, estudantes de outros cursos superiores e alunos de Ensino Médio. As respostas aos questionários foram analisadas utilizando estatística multidimensional, o que permitiu a obtenção de diagramas que refletem a estrutura conceitual compartilhada pelos grupos sociais investigados. À luz dos referenciais teóricos da aprendizagem significativa e das representações sociais, foi possível verificar a existência ou não destas representações, que podem atuar como subsunçores para o ensino de Física, juntamente com outras ideias que compõem a ecologia representacional mental do aprendiz. Algumas dessas ideias podem ter sofrido a influência de meios de divulgação, como mídia, livros e filmes. Esses meios auxiliam na propagação de conceitos científicos - ou quase científicos - influenciam o conhecimento das pessoas, por isso se faz necessário investigar qual o significado atribuído a tais conceitos na elaboração de representações sociais. Os resultados indicam a existência de representações sociais compartilhadas entre sujeitos de alguns grupos investigados, permitindo sua identificação e caracterização. Foram encontrados indícios da influência dos meios de divulgação nas representações sociais dos alunos de Ensino Médio, que devem ser mais bem estudados em trabalhos futuros. / A preliminary study regarding possible social representations of quantum physics among students from different social groups is described. Based on an initial survey on word associations to the expression "quantum physics" a questionnaire was constructed including a test of written concept associations (WCA) and a test of numerical concept association (NCA). This questionnaire was answered by 494 students, divided into three groups: physics undergraduate students, high school students, and undergraduate students from subjects other than physics. Data was analysed using the multidimensional scaling technique which provided spatial diagrams that reflect the conceptual structure shared by the investigated social groups. In the theoretical framework of the meaningful learning and social representations theories it was possible to gather evidences of the existence or not of social representations which may act as subsumers in the learning of physics together with other representations that constitute the mental representational ecology of the learners. Some of these representations might be an effect of information provided by books, movies and other media. This media disseminate information regarding scientific - or almost scientific concepts - and influence people's knowledge. Given that previous knowledge is the main variable influencing the acquisition of knew knowledge it is important to investigate the social representations resulting from this dissemination of information. Research findings suggest the existence of social representations about quantum physics shared by some of the subjects and groups studied. Specially in the case of high school students some evidence was obtained about the existence of social representations that should be more explored in future studies.

Doctor of Philosophy / Department of Physics / Bharat Ratra / The last decade of the 20th century was marked by the discovery of the accelerated expansion of the universe. This discovery puzzles physicists and has yet to be fully understood. It contradicts the conventional theory of gravity, i.e. Einstein’s General Relativity (GR). According to GR, a universe filled with dark matter and ordinary matter, i.e. baryons, leptons, and photons, can only expand with deceleration. Two approaches have been developed to study this phenomenon. One attempt is to assume that GR might not be the correct description of gravity, hence a modified theory of gravity has to be developed to account for the observed acceleration of the universe’s expansion. This approach is known as the ”Modified Gravity Theory”. The other way is to assume that the energy budget of the universe has one more component which causes expansion of space with acceleration on large scales. Dark Energy (DE) was introduced as a hypothetical type of energy homogeneously filling the entire universe and very weakly or not at all interacting with ordinary and dark matter. Observational data suggest that if DE is assumed then its contribution to the energy budget of the universe at the current epoch should be about 70% of the total energy density of the universe. In the standard cosmological model a DE term is introduced into the Einstein GR equations through the cosmological constant, a constant in time and space, and proportional to the metric tensor g[subscript]mu[subscript]nu. While this model so far fits most available observational data, it has some significant conceptual shortcomings. Hence there are a number of alternative cosmological models of DE in which the dark energy density is allowed to vary in time and space.

abstract: In mesoscopic physics, conductance fluctuations are a quantum interference phenomenon that comes from the phase interference of electron wave functions scattered by the impurity disorder. During the past few decades, conductance fluctuations have been studied in various materials including metals, semiconductors and graphene. Since the patterns of conductance fluctuations is related to the distributions and configurations of the impurity scatterers, each sample has its unique pattern of fluctuations, which is considered as a sample fingerprint. Thus, research on conductance fluctuations attracts attention worldwide for its importance in both fundamental physics and potential technical applications. Since early experimental measurements of conductance fluctuations showed that the amplitudes of the fluctuations are on order of a universal value (e2/h), theorists proposed the hypothesis of ergodicity, e.g. the amplitudes of the conductance fluctuations by varying impurity configurations is the same as that from varying the Fermi energy or varying the magnetic field. They also proposed the principle of universality; e.g., that the observed fluctuations would appear the same in all materials. Recently, transport experiments in graphene reveal a deviation of fluctuation amplitudes from those expected from ergodicity. Thus, in my thesis work, I have carried out numerical research on the conductance fluctuations in GaAs nanowires and graphene nanoribbons in order to examine whether or not the theoretical principles of universality and ergodicity hold. Finite difference methods are employed to study the conductance fluctuations in GaAs nanowires, but an atomic basis tight-binding model is used in calculations of graphene nanoribbons. Both short-range disorder and long-range disorder are considered in the simulations of graphene. A stabilized recursive scattering matrix technique is used to calculate the conductance. In particular, the dependence of the observed fluctuations on the amplitude of the disorder has been investigated. Finally, the root-mean-square values of the amplitude of conductance fluctuations are calculated as a basis with which to draw the appropriate conclusions. The results for Fermi energy sweeps and magnetic field sweeps are compared and effects of magnetic fields on the conductance fluctuations of Fermi energy sweeps are discussed for both GaAs nanowires and graphene nanoribbons. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2015

abstract: This thesis develops molecular models for electron transport in molecular junctions and intra-molecular electron transfer. The goal is to identify molecular descriptors that afford a substantial simplification of these electronic processes. First, the connection between static molecular polarizability and the molecular conductance is examined. A correlation emerges whereby the measured conductance of a tunneling junction decreases as a function of the calculated molecular polarizability for several systems, a result consistent with the idea of a molecule as a polarizable dielectric. A model based on a macroscopic extension of the Clausius-Mossotti equation to the molecular domain and Simmon’s tunneling model is developed to explain this correlation. Despite the simplicity of the theory, it paves the way for further experimental, conceptual and theoretical developments in the use of molecular descriptors to describe both conductance and electron transfer. Second, the conductance of several biologically relevant, weakly bonded, hydrogen-bonded systems is systematically investigated. While there is no correlation between hydrogen bond strength and conductance, the results indicate a relation between the conductance and atomic polarizability of the hydrogen bond acceptor atom. The relevance of these results to electron transfer in biological systems is discussed. Hydrogen production and oxidation using catalysts inspired by hydrogenases provides a more sustainable alternative to the use of precious metals. To understand electrochemical and spectroscopic properties of a collection of Fe and Ni mimics of hydrogenases, high-level density functional theory calculations are described. The results, based on a detailed analysis of the energies, charges and molecular orbitals of these metal complexes, indicate the importance of geometric constraints imposed by the ligand on molecular properties such as acidity and electrocatalytic activity. Based on model calculations of several intermediates in the catalytic cycle of a model NiFe complex, a hypothetical reaction mechanism, which very well agrees with the observed experimental results, is proffered. Future work related to this thesis may involve the systematic analysis of chemical reactivity in constrained geometries, a subject of importance if the context of enzymatic activity. Another, more intriguing direction is related to the fundamental issue of reformulating Marcus theory in terms of the molecular dielectric response function. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2015