Organic photovoltaic (OPV) cells are advanced, newly emerging technologies that are lightweight, mechanically flexible devices with highthroughput processes from low cost material in a variety of colors. Rathnayake et al. of Western Kentucky University have developed a nanostructure-based OPV cell. Presented in this thesis is a model and simulation of a generalized PV powered system that can predict the performance of solar arrays in various environmental conditions. The simulation has been carried out in Matlab/Simulink, and upon entering the cell’s parameters, it provides key electrical characteristics such as the cell’s I-V curve and efficiency information. The total system that is simulated consists of three elements: a universal two-cell solar array that can account for partial shading and manufacturing variation, a current-controlled power converter, and an energy storage device with charging and discharging capabilities.

Dans ce travail de thèse nous nous sommes intéressés à une catégorie spécifique d'états quantiques de la lumière : les états non-gaussiens. Ces états ont la particularité de présenter des fonctions de Wigner à valeurs négatives. Cette propriété est indispensable pour réaliser des opérations de calcul quantique mais trouve aussi des applications variées en communication quantique ou métrologie par exemple. Différentes stratégies peuvent être utilisées pour générer de tels états. Ici, les ressources initiales sont des états dit gaussiens produits par des oscillateurs paramétriques optiques en régime continu (i.e. vide comprimé bi-mode et mono-mode). Le caractère non-gaussien ne peut être obtenu que par des phénomènes non-linéaires (hamiltonien sur-quadratique). Dans notre cas, la non-linéarité est induite par des mesures basées sur le comptage de photon (aussi appelées mesures non-gaussiennes). Cette étude est principalement divisée en deux parties. Tout d'abord, la génération d'états non-classiques correspondants à deux types d'encodages de qubits : le photon unique, utilisé en information quantique dite à variables discrètes, et la superposition d'états cohérents (chat de Schrödinger optique), utilisée en information quantique dite à variables continues. Ces états ont ensuite été utilisés pour mettre en \oe{}uvre deux protocoles d'information quantique. Le premier porte sur un témoin d'intrication en photon unique, l'autre sur la génération d'intrication entre deux types d'encodages (aussi appelée intrication hybride).

Single photons - discrete wavepackets of light - are one of the most fundamental entities in physics. In recent years, the ability to consistently create and manipulate both single photons and pairs of photons has facilitated everything from tests of quantum theory to the implementation of quantum-enhanced precision measurements. These activities all fall within the scope of the rapidly-growing field of quantum information - the exploitation of the properties of quantum states (and specifically their capability to exist in superpositions) to accomplish tasks that would not be possible with classical objects. One stated goal of research in quantum information is to build a device consisting of a network of quantum logic gates that can evaluate quantum algorithms. The photonic implementation of individual logic gates has already been demonstrated. However, partly due to standard methods of preparing single photons, current schemes have severe limitations in terms of scaling up from a single logic gate to multiple concatenated operations. Until now it has not been proven that single photons can be generated in pure and indistinguishable quantum states, something upon which the successful operation of optical quantum logic gates relies. This thesis presents an experimental demonstration of simultaneous generation of almost identical single photons in highly pure states from two independent sources based on parametric downconversion. This is a process of photon pair generation during the passage of a light beam through a nonlinear crystal; one photon from the resulting pair is detected to herald the other. The work herein describes, refines, and implements a technique that minimises the strong quantum correlations usually present within each pair by spectral engineering of the source. This allows the heralded single photons to be in pure states, a property that is confirmed by observing a high-visibility two-photon interference effect without spectral filtering.

Theoretical work in quantum information has demonstrated that a classical hidden-variable model of an entangled singlet state can explain nonclassical correlations observed in tests of Bell’s inequality if while measuring the Bell correlation, the underlying probability distribution of the hidden-variable changes depending on the measurement basis. To rule out this possibility, distant quasars can be utilized as random number generators to set measurement bases in an experimental test of Bell’s inequality. Here we report on the design and characterization of a device that uses the color of incoming quasar photons to output a random bit with nanosecond latency. Through the 1-meter telescope at JPL Table Mountain Observatory, we observe and generate random bits from quasars with redshifts z = 0.1−3.9. In addition, we formulate a mathematical model that quantifies the fidelity of the bits generated.

When doing computations on the negatively (positively) charged NV-center in diamond, the common procedure is to add (subtract) an electron from the system. However, when using periodic boundary conditions, this addition/subtraction of an electron from the supercell would result in a divergent electrostatic energy. So an artificial background jellium charge of opposite charge that compensate the electronic charge to make the supercell neutral is needed. This introduces further problems that needs corrections. And this method is especially problematic for slab supercells, as the compensating background charge leads to a dipole, which diverges as the vacuum between the slab images increases. An alternative, recently proposed way of charging the NV-center is to introduce electron donors/acceptors in the form of nitrogen/boron atoms (at substitutional sites in the diamond lattice). In this way, we keep the supercell/slab neutral, and avoid correction schemes. In this work we verify that the addition of a substitutional nitrogen atom indeed has the same effect on the NV-center as the more traditional method of adding an extra electron to the system. Further, we investigate the effects of 1. Adding two substitutional nitrogen atoms to the system (3 nitrogen atoms in total, neutral supercell), 2. Adding a substitutional nitrogen atom and an electron to the system (2 nitrogen atom in total, negatively charged supercell), 3. Adding two electrons to the system (1 nitrogen atom, doubly negatively charged supercell). Additionally, we investigate the addition of acceptor dopants (boron) in order to analyze the effect on the electronic structure of the NV-center and diamond.

Observa-se uma expressiva expansão de mestrados profissionais (MP) na área de Ensino desde a homologação pela Capes, em 2001. Esta dissertação de mestrado analisa trabalhos e produtos educacionais criados no âmbito dos Mestrados Profissionais em Ensino de Física, na área do Ensino de Mecânica Quântica, em uma específica universidade federal. A pesquisa apoia-se em uma análise do discurso, tratando o Trabalho de Conclusão (dissertação+produto educacional) como um enunciado no sentido Bakhtiniano. A partir desta análise, destacamos uma série de inconsistências que permeiam desde o referencial teórico, em muitos casos usado apenas de forma a cumprir exigências sem que seja articulado significativamente à proposta metodológica, até referências que aparecem apenas para contemplar determinados grupos onde o autor está inserido. Por fim destacamos a pouca relevância dos Produtos Educacionais produzidos, não atendendo às demandas escolares e, em muitos casos, trilhando um sentido oposto às pesquisas na área de Ensino de Física. / A significant expansion of professional master’s degree (PM) in the field of Science Education is observed, since its approval in 2001. This dissertation analyses works and educational products created in the scope of professional master’s degree in Physics Teaching, focusing the topic of Quantum Physics Teaching, developed in a federal university. The research relies on a bakhtinian analysis, treating the conclusion work (dissertation + educational product) as an utterance, according to Bakhtin’s theory. From this analysis, it is possible to emphasize a series of inconsistencies that permeate the theoretical framework, in many cases used as a way of fulfilling demands, not significantly articulated to the methodological proposal, also including references that arise only to contemplate certain groups in which the author is inserted. Finally, it is highlighted the low relevance of educational products produced, which do not meet the schools’ demands, and, in many cases, follow an opposite way if compared to researches in the area of Physics Education.

This thesis supports the Master of Fine Arts exhibition at the Slocumb Galleries in Ball Hall at East Tennessee State University, from February 23rd through February 27th 2009. The exhibition is comprised of eight graphite drawings, one ink drawing, eight vinyl prints, two hundred sixty lenticular prints, over fifty digital inkjet prints, and one video installation. The exhibition presents the artist's exploration into using drawings and prints as installation as they relate to quantum physics and universal scale. Subjects discussed, on a project-by-project basis, include thought, ideas, methods, influences, and process by which the work in the exhibition was achieved.

We investigate the energy levels of a particle confined in the isotropic oscillator potential with a magnetic and spatially varying electric field. Here we are able to exactly solve the Schrodinger equation, using matrix methods, for the first excited states. To this end we find that the spatial gradient of the electric field acts as a magnetic field in certain circumstances. Here we present the changes in the energy levels as functions of the electric field, and other parameters.

This volume provides a comprehensive introduction to the theory of electronic motion in molecular processes an increasingly relevant and rapidly expanding segment of molecular quantum dynamics. Emphasis is placed on describing and interpreting transitions between electronic states in molecules as they occur typically in cases of reactive scattering between molecules, photoexcitation or nonadiabatic coupling between electronic and nuclear degrees of freedom. Electron Dynamics in Molecular Interactions aims at a synoptic presentation of some very recent theoretical efforts to solve the electronic problem in quantum molecular dynamics, contrasting them with more traditional schemes. The presented models are derived from their roots in basic quantum theory, their interrelations are discussed, and their characteristic applications to concrete chemical systems are outlined. This volume also includes an assessment of the present status of electron dynamics and a report on novel developments to meet the current challenges in the field. Further, this monograph responds to a need for a systematic comparative treatise on nonadiabatic theories of quantum molecular dynamics, which are of considerably higher complexity than the more traditional adiabatic approaches and are steadily gaining in importance. This volume addresses a broad readership ranging from physics or chemistry graduate students to specialists in the field of theoretical quantum dynamics. / https://dc.etsu.edu/etsu_books/1055/thumbnail.jpg

Dans la course à l’ordinateur quantique, le silicium est devenu ces dernières années un matériau de choix pour l'implémentation des qubits de spin. De tels dispositifs sont fabriqués au CEA en utilisant les technologies CMOS, afin de faciliter leur intégration à grande échelle. Cette thèse porte sur la modélisation de ces qubits, et en particulier sur la manipulation de l’état de spin par un champ électrique. Pour cela nous utilisons un ensemble de techniques numériques avancées pour calculer le potentiel et la structure électronique des qubits (notamment les méthodes de liaisons fortes et k.p), afin d’être le plus proche possible des dispositifs expérimentaux. Ces simulations nous ont permis d’étudier deux résultats expérimentaux d’importance : l’observation de la manipulation par champ électrique du spin d’un électron d’une part, et la caractérisation de l’anisotropie de la fréquence de Rabi d’un qubit de trou d’autre part. Le premier résultat était plutôt inattendu, étant donné; le très faible couplage spin-orbite dans la bande de conduction du silicium. Nous développons un modèle, validé par les simulations et certains résultats expérimentaux, qui met en évidence le rôle essentiel du couplage spin-orbite inter-vallée, exacerbé par la faible symétrie du système. Nous utilisons ces résultats pour proposer et tester numériquement un schéma de manipulation électrique consistant à passer réversiblement d’un qubit de spin à un qubit de vallée. Concernant les qubits de trous, le couplage spin-orbite relativement élevé autorise la manipulation du spin par champ électrique, toutefois les mesures expérimentales d’anisotropie donnent à voir une physique complexe, insuffisamment bien décrite par les modèles actuels. Nous développons donc un formalisme permettant de caractériser simplement la fréquence de Rabi en fonction du champ magnétique, et qui peut s’appliquer à d’autre type de qubit spin-orbite. Les simulations permettent de reproduire les résultats expérimentaux, et de souligner le rôle important de la contrainte. / In the race for quantum computing, these last years silicon has become a material of choice for the implementation of spin qubits. Such devices are fabricated in CEA using CMOS technologies, in order to facilitate their large-scale integration. This thesis covers the modeling of these qubits andin particular the manipulation of the spin state with an electric field. To that end, we use a set numerical tools to compute the potential and electronic structure in the qubits (in particular tightbinding and k.p methods), in order to be as close as possible to the experimental devices. These simulations allowed us to study two important experimental results: on one hand the observation of the electrical manipulation of an electron spin, and on the other hand the characterization of the anisotropy of the Rabi frequency of a hole spin qubit. The first one was rather unexpected, since the spin-orbit coupling is very low in the silicon conduction band. We develop a model, confirmed by thesimulations and some experimental results, that highlights the essential role of the intervalley spinorbit coupling, enhanced by the low symmetry of the system. We use these results to propose and test numerically a scheme for electrical manipulation which consists in switching reversibly betweena spin qubit and a valley qubit. Concerning the hole qubits, the relatively large spin-orbit coupling allows for electrical spin manipulation. However the experimental measurements of Rabi frequency anisotropy show a complex physics, insufficiently described by the usual models. Therefore we developa formalism which allows to characterize simply the Rabi frequency as a function of the magnetic field, and that can be applied to other types of spin-orbit qubits. The simulations reproduce the experimental features, underline the important role of strain.