O trabalho apresenta uma análise e descrição, do tipo estudo de caso, das estratégias enunciativas utilizadas por duas futuras professoras de física que implementaram uma sequência didática sobre tópicos de Mecânica Quântica. As aulas foram estruturadas como aulas invertidas, em que se utilizou o peer instruction (instrução pelos colegas) como metodologia ativa, e fizeram parte de um minicurso de 8 horas de duração dirigido a alunos do Ensino Médio. O minicurso foi realizado por professores em formação do Curso de Licenciatura em Ciências Exatas, do Instituto de Física da USP de São Carlos, bolsistas do projeto PIBID/CAPES no ano de 2013. A análise das estratégias enunciativas foi feita utilizando-se da ferramenta analítica proposta por Mortimer e Scott (2003) levando em conta um conjunto de modos de comunicação. O objetivo é caracterizar o discurso de professoras em um contexto de inovação curricular utilizando uma metodologia ativa de aprendizagem. As intenções e intervenções dos professores, a abordagem comunicativa estabelecida em sala de aula, os padrões e os conteúdos das interações foram analisados. Os resultados apontam que as futuras professoras utilizaram abordagens interativas dialógicas e de autoridade para mediar a discussão entre os pares e que nenhuma das abordagens é superior a outra para realizar as mediações em sala de aula. As abordagens interativas dialógicas foram usadas com um padrão de interação do tipo I-R-F (iniciação-resposta e feedback), as abordagens de autoridade foram usadas com padrões de interação do tipo I-R-A (iniciação- reposta- avaliação). Foram identificados três momentos na instrução pelos colegas de ambas futuras professoras: o compartilhamento de alternativas, a discussão das ideias e o fechamento das discussões. Esses estágios foram relacionados as intenções e intervenções estabelecidas pelas futuras professora. A abordagem interativa dialógica na aplicação da instrução pelos colegas se mostrou mais adequada que outras abordagens. O trabalho visa contribuir para o avanço das pesquisas na formação de professores em um contexto de inovação curricular ampliando interpretações dos mecanismos e processos envolvidos na formação inicial de professores de Física, quando estes trabalham com metodologias interativas de ensino, em particular, o método de Instrução pelos Colegas (Peer Instruction). / This thesis presents an analysis and description of the case study type, the declared strategies used by two future physics teachers who implemented a teaching sequence on topics of Quantum Mechanics. The classes were structured as flipped classroom, which used the peer instruction as active methodology, and took part in a short course of eight hours\' duration aimed at high school students. The short course was held for teachers in training of Sciences Degree Course of the Institute of Physics of São Carlos, fellows PIBID project / CAPES in 2013. The analysis of the declared strategies was performed using the analytical tool proposed by Mortimer and Scott (2003) taking into account a range of modes of communication. The goal is to characterize the speech of teachers in a curriculum innovation context using an active learning methodology. The tool analyzed the intentions and activities of the teachers, the communicative approach set out in the classroom, the patterns and the interactions content. The results show that future teachers used dialogical and interactive approaches authority to mediate the argument between the couple and that neither approach is superior to another to conduct mediations in the classroom. Dialogical interactive approaches were used with a pattern of interaction type IRF (initiation-answer and feedback), the authority of approaches were used with IRE kind of interaction patterns (initiation- answer- evaluation). Three moments in education by peers of both future teachers were identified: alternative sharing, discussion of ideas and the closure of the discussions. These stages were related intentions and interventions established by future teachers. The dialogic interactive approach to education application by colleagues was more appropriate than other approaches. This work aims to contribute to the advancement of research in teacher education in a curriculum innovation context expanding interpretations of the mechanisms and processes involved in the initial formation of physics teachers when they work with interactive teaching methodologies, in particular, the peer instruction.

O trabalho apresenta uma análise e descrição, do tipo estudo de caso, das estratégias enunciativas utilizadas por duas futuras professoras de física que implementaram uma sequência didática sobre tópicos de Mecânica Quântica. As aulas foram estruturadas como aulas invertidas, em que se utilizou o peer instruction (instrução pelos colegas) como metodologia ativa, e fizeram parte de um minicurso de 8 horas de duração dirigido a alunos do Ensino Médio. O minicurso foi realizado por professores em formação do Curso de Licenciatura em Ciências Exatas, do Instituto de Física da USP de São Carlos, bolsistas do projeto PIBID/CAPES no ano de 2013. A análise das estratégias enunciativas foi feita utilizando-se da ferramenta analítica proposta por Mortimer e Scott (2003) levando em conta um conjunto de modos de comunicação. O objetivo é caracterizar o discurso de professoras em um contexto de inovação curricular utilizando uma metodologia ativa de aprendizagem. As intenções e intervenções dos professores, a abordagem comunicativa estabelecida em sala de aula, os padrões e os conteúdos das interações foram analisados. Os resultados apontam que as futuras professoras utilizaram abordagens interativas dialógicas e de autoridade para mediar a discussão entre os pares e que nenhuma das abordagens é superior a outra para realizar as mediações em sala de aula. As abordagens interativas dialógicas foram usadas com um padrão de interação do tipo I-R-F (iniciação-resposta e feedback), as abordagens de autoridade foram usadas com padrões de interação do tipo I-R-A (iniciação- reposta- avaliação). Foram identificados três momentos na instrução pelos colegas de ambas futuras professoras: o compartilhamento de alternativas, a discussão das ideias e o fechamento das discussões. Esses estágios foram relacionados as intenções e intervenções estabelecidas pelas futuras professora. A abordagem interativa dialógica na aplicação da instrução pelos colegas se mostrou mais adequada que outras abordagens. O trabalho visa contribuir para o avanço das pesquisas na formação de professores em um contexto de inovação curricular ampliando interpretações dos mecanismos e processos envolvidos na formação inicial de professores de Física, quando estes trabalham com metodologias interativas de ensino, em particular, o método de Instrução pelos Colegas (Peer Instruction). / This thesis presents an analysis and description of the case study type, the declared strategies used by two future physics teachers who implemented a teaching sequence on topics of Quantum Mechanics. The classes were structured as flipped classroom, which used the peer instruction as active methodology, and took part in a short course of eight hours\' duration aimed at high school students. The short course was held for teachers in training of Sciences Degree Course of the Institute of Physics of São Carlos, fellows PIBID project / CAPES in 2013. The analysis of the declared strategies was performed using the analytical tool proposed by Mortimer and Scott (2003) taking into account a range of modes of communication. The goal is to characterize the speech of teachers in a curriculum innovation context using an active learning methodology. The tool analyzed the intentions and activities of the teachers, the communicative approach set out in the classroom, the patterns and the interactions content. The results show that future teachers used dialogical and interactive approaches authority to mediate the argument between the couple and that neither approach is superior to another to conduct mediations in the classroom. Dialogical interactive approaches were used with a pattern of interaction type IRF (initiation-answer and feedback), the authority of approaches were used with IRE kind of interaction patterns (initiation- answer- evaluation). Three moments in education by peers of both future teachers were identified: alternative sharing, discussion of ideas and the closure of the discussions. These stages were related intentions and interventions established by future teachers. The dialogic interactive approach to education application by colleagues was more appropriate than other approaches. This work aims to contribute to the advancement of research in teacher education in a curriculum innovation context expanding interpretations of the mechanisms and processes involved in the initial formation of physics teachers when they work with interactive teaching methodologies, in particular, the peer instruction.

The field of quantum mechanics has revolutionised physics as a subject. Areas such as information theory, computer science and physical sensing have all been affected by the tremendous successes of various quantum protocols. In this thesis I present my contribution to the development of such non-classical protocols. In classical communication theory a message is always carried by physical particles that interact with a transmitter, after which they travel to a receiver. In this thesis I outline a quantum protocol which allows a receiver to obtain a message without receiving any physical object or particles that have interacted with the transmitter-that is, counterfactually. I build my protocol for counterfactual communication on the principles of interaction-free measurements, ensuring that information always propagates in the opposite direction to the protocol particles. The protocol shows how quantum mechanics breaks the previous premise of communication theory. From the perspective of local observers, it is a beautiful manifestation of the non-locality of interaction-free measurements. Furthermore, it is highly robust against experimental errors and external disturbances. The majority of this part of the thesis is based on my published article 'Quantum counterfactual communication without a weak trace' [Phys. Rev. A 94, 062303 (2016)]. Previous to my work, Salih et al. attempted to design a counterfactual communication protocol [Phys. Rev. Lett. 110, 170502 (2013)]. This protocol has been highly controversial. As counterfactual phenomena impose restrictions on the inter-measurement paths of quantum particles, and the physical reality of such paths lacks description in the Copenhagen interpretation of quantum mechanics, an extension of current quantum theory is required to facilitate a discussion. In this thesis I present an operational and interpretation-independent methodology, enabling the discussion of inter-measurement paths of quantum particles. I start by considering the interferometers of counterfactual protocols, making the basic assumption that any quantum evolution naturally involves uncontrolled weak interactions. I then show how the Fisher information of these weak interactions, available at the output of counterfactual experiments, can be used to discuss the pre-measurement past of the particles. Based on this analysis, the protocol developed by Salih et al. is found to strongly violate counterfactuality. However, my protocol is more flexible in that it allows particles to propagate in the opposite direction to the message. This leads to counterfactuality being satisfied-even in the presence of large experimental errors. These results are observed both analytically and numerically. This part of the thesis is based on my article 'Evaluation of counterfactuality in counterfactual communication protocols' [Phys. Rev. A 96, 062316 (2017)]. The numerical methods are inspired by another of my publications: 'Protocol for fermionic positive-operator-valued measures' [Phys. Rev. A 96, 052305 (2017)]. Finally, as the Fisher information measure is found to be useful in evaluating counterfactual protocols, I extend my work by investigating the quantum Fisher information in experiments with general discrete quantum circuits. I prove that the quantum Fisher information of a two-level interaction in a quantum circuit can be expressed by a simple formula. Under certain phase-relations, the formula provides a straightforward connection between the abstract concept of the inter-measurement wavefunction and the quantum Fisher information at the output. With regard to how the information obtained from a certain volume of space influences our perception of classical objects, I argue that the quantum Fisher information measure is highly useful in describing quantum objects. If this measure is applied to observers with a limited set of the experimental measurement outcomes, a quantum object can appear to follow non-classical discontinuous paths. This supports the remarkable conclusion that our perception of the past of a quantum object is subjectively dependent on the measurement we conduct on it.

Processing Information: Rhymes and Reasons

After an introduction to the variational principle of three body systems via the Helium atom, we present general analytical formulas for the radial parts of integrals that occur when three body systems are described using wave functions that consist of powers and exponentials in all three interparticle Hylleraas coordinates [Hylleraas1929]. This work is an extension of integrals given by Harris, Frolov and Smith, Jr. [Harris2004]. Specifically included are radial integrals encountered in calculations involving the dipole moment matrix element in Hylleraas coordinates that contain a function f(kr1) (such as a spherical Bessel function) in addition to a plane wave, a hydrogenic orbital and exponentials in all three interparticle coordinates.

This work is motivated by two non-intuitive predictions of Quantum Mechanics: non-locality and contextuality. Non-locality is a phenomenon whereby interactions between spatially separated objects appear to be occurring faster than the speed of light. Contextuality is a phenomenon whereby the outcome of a measurement cannot be interpreted as the revelation of an intrinsic fixed property of the system being measured, but instead necessarily depends on the configuration of the measurement apparatus. Quantum Mechanics predicts non-local behavior in certain types of experiments collectively known as Bell tests. However, ruling out all possible alternative local theories is a subtle and demanding task. In this work, we lay out a mathematically-rigorous framework for analyzing Bell experiments. Using this framework, we derive the famous Clauser-Horne-Shimony-Holt (CHSH) inequality, an important constraint that is obeyed by all local theories and violated by Quantum Mechanics. We further demonstrate how to analyze the data of a CHSH experiment without assuming that successive experimental trials are independent and/or identically distributed. We also derive the Clauser-Horne (CH74) inequality, an inequality that is more well-suited for realistic Bell experiments using photons. We demonstrate a robust method for statistically analyzing the data of a CH74 experiment, and show how to calculate exact p-values for this analysis, improving on the previously-best-known (loose) upper bounds obtained from Hoeffding-style inequalities. The work concludes with an exploration of contextuality. The Kochen-Specker theorem -- a result demonstrating the contextual nature of Quantum Mechanics -- is applied to resolve a conjecture in Domain Theory regarding the spectral order on quantum states. / acase@tulane.edu

In this thesis, we present a systematic investigation of the static and dynamic response properties of low-dimensional systems, using a variety of theoretical techniques ranging from time dependent density functional theory to the recursive Green's function method. As typical low-dimensional systems, metal nanostructures can strongly interact with an electric field to support surface plasmons, making their optical properties extremely attractive in both fundamental and applied aspects. We have investigated the energy broadening of surface plasmons in metal structures of reduced dimensionality, where Landau damping is the dominant dissipation channel and presents an intrinsic limitation to plasmonics technology. We show that for every prototype class of systems considered, including nanoshells, coaxial nanotubes, and ultrathin films, Landau damping can be drastically tuned due to energy quantization of the individual electron levels and e-h pairs. Both the generic trend and oscillatory nature of the tunability are in stark contrast with the expectations of the semiclassical surface scattering picture. For a more realistic environment of low-dimensional systems, the effect of a dielectric substrate is considered to mimic the experimental setup. We have studied the dispersion of various plasmon excitations in metal thin films with growth substrates. Our results qualitatively reproduce the experimentally observed plasmon spectra of the Mg/Si systems. The underlying physics for the formation of various absorption peaks can be understood with a simple hybridization concept. Based on this concept, the coexistence of surface and bulk plasmons in experimental observation turns out to be a clear evidence for the existence of multiple-multipole surface plasmons due to the quantum confinement in thin films. To step into more confined worlds, we choose the real two-dimensional material graphene as our representive system, which is a semi-metal with zero band-gap. As the first step, the static electric response of graphene is investigated by exploring its transport properties. We have studied the pseudospin valve effect in bilayer graphene nanoribbons. The pseudospin degree of freedom is associated with the electron density in two layers and can be controlled by external gate electrodes. We find that the conductance of nanoribbons shows different behaviors compared with infinite systems due to the appearance of edge states and quantum confinement. Remarkably, a large on-off ratio can be achieved in nanoribbons with zigzag edges, even when the Fermi energy lies in the bulk energy gap. The influence of possible edge vacancies and interface conditions is also discussed. Finally, we discuss the possibility of using plasmon excitations to detach the graphene from its growth substrate, where the dynamic electric response of the graphene-metal system is expected to play a central role.

Depuis son invention en 1984 par C.H. Bennett et G. Brassard, le protocole BB84 a été prouvé sûr contre les attaques les plus générales autorisées par la mécanique quantique, les attaques cohérentes. Cependant, afin de réaliser ces attaques, un adversaire a besoin de mémoire quantique et il n'existe pas à l'heure actuelle de technologie permettant de créer facilement de telles mémoires. Il est donc important de savoir quantifier plus précisément la puissance de l'adversaire lorsque celui-ci n'a pas accès à une mémoire quantique parfaite. Ces nouveaux modèles de sécurité où la puissance de l'adversaire est limitée par des contraintes plus ou moins fortes sur sa mémoire quantique ont été déjà développés et utilisés pour étudier la sécurité des protocoles réalisant une fonction cryptographique à deux participants (comme la mise en gage de bit quantique par exemple). L'objectif de cette thèse a été d'adapter ces modèles de sécurité à l'étude de la sécurité des protocoles de distribution quantique de clés. Nous avons ainsi pu étudier la sécurité des principaux protocoles de distribution quantique de clés dans le cas où l'adversaire n'a pas de mémoire quantique et dans un modèle plus général où il est limité par le bruit de sa mémoire. Ces recherches ont permis de mieux comprendre l'influence de la qualité de la mémoire quantique sur la puissance des attaques et ainsi de quantifier le compromis entre la performance d'un protocole (en terme de taux de clé ou de distance atteignable) et la sécurité désirée.

This thesis reports experimental observations of electric fields using Rydberg atoms, including dc field measurements near the surface of an atom chip, and demonstration of measurement techniques for ac fields far from the surface. Associated theoretical results are also presented, including Monte Carlo simulations of the decoherence of Rydberg states in electric field noise as well as an analytical calculation of the statistics of dc electric field inhomogeneity near polycrystalline metal surfaces. DC electric fields were measured near the heterogeneous metal and dielectric surface of an atom chip using optical spectroscopy on cold atoms released from the trapping potential. The fields were attributed to charges accumulating in the dielectric gaps between the wires on the chip surface. The field magnitude and direction depend on the details of the dc biasing of the chip wires, suggesting that fields may be minimized with appropriate biasing. Techniques to measure ac electric fields were demonstrated far from the chip surface, using the decay of a coherent superposition of two Rydberg states of cold atoms. We have used the decay of coherent Rabi oscillations to place some bounds on the magnitude and frequency dependence of ac field noise. The rate of decoherence of a superposition of two Rydberg states was calculated with Monte Carlo simulations. The states were assumed to have quadratic Stark shifts and the power spectrum of the electric field noise was assumed to have a power-law dependence of the form 1/f^κ. The decay is exponential at long times for both free evolution of the superposition and and Hahn spin-echo sequences with a π refocusing pulse applied to eliminate the effects of low-frequency field noise. This decay time may be used to calculate the magnitude of the field noise if κ is known. The dc field inhomogeneity near polycrystalline metal surfaces due to patch potentials on the surface has been calculated, and the rms field scales with distance to the surface as 1/z^2. For typical evaporated metal surfaces the magnitude of the rms field is comparable to the image field of an elementary charge near the surface.

This thesis focuses on pioneering a scalable route to fabricate quantum information devices based upon single InAs/InP quantum dots emitting in the telecommunications wavelength band around 1550 nm. Using metallic gates in combination with nanotemplate, site-selective epitaxy techniques, arrays of single quantum dots are produced and electrostatically tuned with a high degree of control over the electrical and optical properties of each individual quantum dot. Using metallic gates to apply local electric fields, the number of electrons within each quantum dot can be tuned and the nature of the optical recombination process controlled. Four electrostatic gates mounted along the sides of a square-based, pyramidal nanotemplate in combination with a flat metallic gate on the back of the InP substrate allow the application of electric fields in any direction across a single quantum dot. Using lateral fields provided by the metallic gates on the sidewalls of the pyramid and a vertical electric field able to control the charge state of the quantum dot, the exchange splitting of the exciton, trion and biexciton are measured as a function of gate voltage. A quadrupole electric field configuration is predicted to symmetrize the product of electron and hole wavefunctions within the dot, producing two degenerate exciton states from the two possible optical decay pathways of the biexciton. Building upon these capabilities, the anisotropic exchange splitting between the exciton states within the biexciton cascade is shown to be reversibly tuned through zero for the first time. We show direct control over the electron and hole wavefunction symmetry, thus enabling the entanglement of emitted photon pairs in asymmetric quantum dots. Optical spectroscopy of single InAs/InP quantum dots atop pyramidal nanotemplates in magnetic fields up to 28T is used to examine the dispersion of the s, p and d shell states. The g-factor and diamagnetic shift of the exciton and charged exciton states from over thirty single quantum dots are calculated from the spectra. The g-factor shows a generally linear dependence on dot emission energy, in agreement with previous work on this subject. A positive linear correlation between diamagnetic coefficient and g-factor is observed.