Single atoms on demand for cavity QED experiments

Cavity quantum electrodynamics (cavity QED) describes electromagnetic fields in a confined space and the radiative properties of atoms in such fields. The simplest example of such system is a single atom interacting with one mode of a high-finesse resonator. Besides observation and exploration of fundamental quantum mechanical effects, this system bears a high potential for applications quantum information science such as, e.g., quantum logic gates, quantum communication and quantum teleportation. In this thesis I present an experiment on the deterministic coupling of a single neutral atom to the mode of a high-finesse optical resonator. In Chapter 1 I describe our basic techniques for trapping and observing single cesium atoms. As a source of single atoms we use a high-gradient magneto-optical trap, which captures the atoms from background gas in a vacuum chamber and cools them down to millikelvin temperatures. The atoms are then transferred without loss into a standing-wave dipole trap, which provides a conservative potential required for experiments on atomic coherence such as quantum information processing and metrology on trapped atoms. Moreover, shifting the standing-wave pattern allows us to deterministically transport the atoms (Chapter 2). In combination with non-destructive fluorescence imaging of individual trapped atoms, this enables us to control their position with submicrometer precision over several millimeters along the dipole trap. The cavity QED system can distinctly display quantum behaviour in the so-called strong coupling regime, i.e., when the coherent atom-cavity coupling rate dominates dissipation in the system. This sets the main requirements on the resonator's properties: small mode volume and high finesse. Chapter 3 is devoted to the manufacturing, assembling, and testing of an ultra-high finesse optical Fabry-Perot resonator, stabilized to the atomic transition. In Chapter 4 I present the transportation of single atoms into the cavity and their coupling to the cavity mode. The strong coupling manifests itself in a strong reduction of the cavity transmission probed by a weak external laser. The atoms remain trapped and coupled to the cavity mode for several seconds until we move them out of the cavity for final analysis of their number and position

Behaviour of carbon/epoxy composite sandwich panels with sustainable core materials subjected intermediate velocity impacts

Sandwich composite structures are made of two strong and stiff face-sheets separated by a lightweight core material. They are used in lightweight structures for load-carrying applications in the aerospace, marine, railway and wind-energy industry as a way to increase the bending stiffness and bucking resistance while maintaining a low weight. During their lifetime these structures are subjected to impact events such as the accidental drop of tools during assembly, bird strikes, hailstone impact, or even Foreign Object (FO) impact of stones, debris, etc…. Damage produced by impacts can compromise the integrity of a structure reducing its residual strength and stiffness, causing premature failure of a component under service loads. This PhD thesis studies the mechanical response, impact process, and damage mechanisms taking place in an Intermediate Velocity Impact (IVI) over a sandwich composite panel made of woven carbon/epoxy face-sheets with either agglomerated cork core or PET foam core. This is done by applying a numerical-experimental methodology based on the building block approach used for aircraft certification in which results obtained from numerical models are directly compared with results obtained in the experimental test. In this context, the thesis is divided into three main parts. In the first part of this thesis, the face-sheet and core are treated independently to understand their unique dynamic response and select appropriate constitutive material models for the FEA model implementation. Continuous damaged models are used to model the inter-laminar and intra-laminar fracture behaviour in the face-sheets. The suitability of these models is assessed through the implementation of independent FEA models for fracture tests (modes I & II) and ballistic impact which are validated with experimental experiments from the literature. In the case of the core, the compressive and tensile response of the core materials (agglomerated cork and PET foam) is studied by performing static and dynamic characterization tests. The collected data is then used for the validation of the non-linear material models by implementing an FEA model for dynamic compression. The second part of this thesis studies the IVI event of the whole sandwich panel. This is done by performing a set of experimental impact tests and implementing a detailed explicit/nonlinear FEA model, which is validated against experimental results. The experimental tests are performed using a gas gun together with a different state of the art measuring techniques such as high-speed video recording, 3D Digital Image Correlation x (DIC) and Computed X-ray Tomography (CT). The FEA model is successfully validated and it is used to study the phases and mechanisms of damage evolution present during the impact process, something that is not possible to obtain experimentally and provides a valuable tool to understand the phenomenon. At the most general level, the impact process is dominated by different interacting physical mechanisms such as elastic deformation of the panel, inter-laminar and intra-laminar fracture of the face-sheets, non-linear core deformation, multiaxial core failure and core-face-sheet debonding. Different impact phases are observed and their physical mechanisms explained in detail. The FEA model is also used to perform a comparative analysis of different impact parameters (e.g. impact velocity, core thickness, impact angle, and axial preload) analysing their influence in the mechanical response of the sandwich panels under IVI. The third part of this thesis studies the hailstone impact over the sandwich panels using the developed FEA model of the sandwich panel together with a particles model for the hailstone. The interaction between the dominant physical mechanisms in the sandwich panel (e.g. elastic response, face-sheet damage, core failure, etc…) and the fragmentation of the hailstone are explained in detail together with some failure modes expected in this kind of event and the severity of the impact extended for two different hailstone sizes.Las estructuras tipo sándwich están compuestas a partir de dos placas rígidas y resistentes separadas por un núcleo liviano. Se utilizan en estructuras ligeras en industrias como la aeroespacial, marina, ferroviaria y eólica como una forma de aumentar la rigidez a la flexión y la resistencia al pandeo, manteniendo un peso reducido. Durante su vida útil, estas estructuras están sujetas a eventos de impacto, como la caída accidental de herramientas durante el montaje, impactos de pájaros, impactos de granizo o incluso impactos de objetos extraños (piedras, escombros, etc…). Los daños producidos por impactos pueden comprometer la integridad de una estructura reduciendo su resistencia y rigidez residuales, provocando la falla prematura de un componente bajo cargas de servicio. Esta tesis doctoral estudia la respuesta mecánica, el proceso de impacto y los mecanismos de daño que tienen lugar en un impacto de velocidad intermedia (IVI) sobre un panel sándwich fabricado a partir de laminados de tejido de carbono/epoxi con núcleo de corcho aglomerado o núcleo de espuma PET. El estudio se realiza mediante la aplicación de una metodología numérico-experimental basada en el enfoque de bloques de construcción utilizado típicamente para la certificación de aeronaves en el que los resultados obtenidos de los modelos numéricos se comparan directamente con los resultados obtenidos en la prueba experimental. En este contexto, la tesis se divide en tres partes principales. En la primera parte, el laminado y el núcleo se tratan de forma independiente para comprender su respuesta dinámica única y seleccionar modelos de materiales constitutivos apropiados para la implementación del modelo FEA. Se utilizan modelos de daño continuo para modelar el comportamiento de fractura inter-laminar e intra-laminar en las laminados. La idoneidad de estos modelos se evalúa mediante la implementación de modelos FEA independientes para ensayos de fractura (modos I y II) e impacto balístico que se validan con datos experimentales de la literatura. En el caso del núcleo, se estudia la respuesta a compresión y tracción de los materiales del núcleo (corcho aglomerado y espuma PET) mediante la realización de ensayos de caracterización estática y dinámica. Los datos recopilados se utilizan para validar los modelos de materiales no lineales mediante la implementación de un modelo FEA para compresión dinámica. La segunda parte de esta tesis estudia el evento IVI del panel sándwich completo. Se ha realizado un conjunto de pruebas de impacto experimentales e implementando un modelo FEA explícito/no-lineal detallado que se valida con resultados experimentales. Para las pruebas de impacto se utiliza un cañon de gas empleando diferentes técnicas de medición de última generación como grabación de video de alta velocidad, la correlación de imágenes digitales (DIC) en 3D y tomografía de rayos X computarizada (CT). El modelo FEA se valida satisfactoriamente y se utiliza para estudiar las fases y mecanismos de evolución del daño que ocurren durante el impacto; algo que no es posible experimentalmente y que proporciona una valiosa herramienta para comprender el fenómeno. A nivel general, el proceso de impacto está dominado por diferentes mecanismos físicos que interactúan entre si como la deformación elástica del panel, la fractura inter-laminar e intra-laminar de los laminados, la deformación no lineal del núcleo, la falla multiaxial del núcleo y el despegue entre núcleo y laminado. Se observan diferentes fases de impacto y se explican en detalle sus mecanismos físicos. El modelo FEA también se utiliza para realizar un análisis comparativo de diferentes parámetros del problema (por ejemplo, velocidad de impacto, espesor del núcleo, ángulo de impacto y precarga axial) analizando su influencia en la respuesta mecánica de los paneles sándwich bajo IVI. La tercera parte de esta tesis estudia el impacto del granizo en los paneles sándwich utilizando el modelo FEA desarrollado del panel sándwich junto con un modelo de partículas para el granizo. Se explica en detalle la interacción entre los mecanismos físicos dominantes en el panel sándwich (por ejemplo, respuesta elástica, daño en la cara frontal, falla del núcleo, etc.) y la fragmentación del granizo asi como algunos modos de falla esperados en este tipo de evento y la severidad de la extensión de daño asumiendo dos tamaños diferentes de granizo.Programa de Doctorado en Ingeniería Mecánica y de Organización Industrial por la Universidad Carlos III de MadridPresidente: Jacobo Díaz García.- Secretario: Shirley Kalamis García Castillo.- Vocal: Alberto Solís Fajard

Human retinal oximetry using hyperspectral imaging

The aim of the work reported in this thesis was to investigate the possibility of measuring human retinal oxygen saturation using hyperspectral imaging. A direct non-invasive quantitative mapping of retinal oxygen saturation is enabled by hyperspectral imaging whereby the absorption spectra of oxygenated and deoxygenated haemoglobin are recorded and analysed. Implementation of spectral retinal imaging thus requires ophthalmic instrumentation capable of efficiently recording the requisite spectral data cube. For this purpose, a spectral retinal imager was developed for the first time by integrating a liquid crystal tuneable filter into the illumination system of a conventional fundus camera to enable the recording of narrow-band spectral images in time sequence from 400nm to 700nm. Postprocessing algorithms were developed to enable accurate exploitation of spectral retinal images and overcome the confounding problems associated with this technique due to the erratic eye motion and illumination variation. Several algorithms were developed to provide semi-quantitative and quantitative oxygen saturation measurements. Accurate quantitative measurements necessitated an optical model of light propagation into the retina that takes into account the absorption and scattering of light by red blood cells. To validate the oxygen saturation measurements and algorithms, a model eye was constructed and measurements were compared with gold-standard measurements obtained by a Co-Oximeter. The accuracy of the oxygen saturation measurements was (3.31%± 2.19) for oxygenated blood samples. Clinical trials from healthy and diseased subjects were analysed and oxygen saturation measurements were compared to establish a merit of certain retinal diseases. Oxygen saturation measurements were in agreement with clinician expectations in both veins (48%±9) and arteries (96%±5). We also present in this thesis the development of novel clinical instrument based on IRIS to perform retinal oximetry.Al-baath University, Syri

Testing general relativity at galactic scales

General Relativity (GR) has been successfully tested in Solar system scales. However, for galactic scales, this theory has been poorly tested. Moreover, several galaxy data analysis depend on the value of the Hubble constant (H0), which is currently under discussion. In addition, over the decades, some tensions arose, and GR has not been able to solve them. In this work we implement another test to GR in galactic scales, combining mass measurements for an elliptical lens galaxy. These measurements can be obtained by stellar kinematics and gravitational lensing, which are connected by a γPPN parameter, in the Parametrized Post-Newtonian formalism. This parameter can be derived, in our context, from the ratio of two different potentials: the Newtonian potential Φ, which acts in massive and non-relativistic particles; and the curvature potential Ψ, related to the curvature of space-time and more important to the motion of relativistic and massless particles. If GR is assumed, γPPN = 1. This approach has been implemented by Collet et al. (2018) using a system in which the lens galaxy is at zl = 0.035. In this work they find γPPN = 0.97 ± 0.09. We apply the same methodology for the SDP.81 system in which the lens galaxy is at zl = 0.299, and therefore is much more distant than the object studied by Collett et al. We use data from three state-of-the-art observatories nowadays: ALMA, HST and VLT/MUSE. Besides the test of GR, we are able to study the mass distribution of the lens galaxy, and we found that about 45% of its mass within 1Re = 1.15600 is due to the presence of dark matter, which can be described by a Navarro-Frenk-White profile, in accordance with previous studies using galaxies at similar redshift. However, the main result is the inference of γPPN. We notice that our most likely model was deviating from GR within 1σ, but with a very small statistical error, which shows that our inference is dominated by systematic errors. Previous studies that tried to constrain γPPN had the same problem. Using the expected systematics derived by these previous studies, we are able to draw two possible scenarios. In the worst-case scenario, the systematic effects are of the order of 25%, leaves us with γPPN = 1.0092 ± 0.0001(stat) ± 0.2523(sys), which agrees with GR within 1σ. In the best-case scenario, the systematics are of the order of 9%, and the final inference γPPN = 1.0092 ± 0.0001(stat) ± 0.0908(sys), still in accordance with the GR within 1σ.A Relatividade Geral (RG) tem sido testada com sucesso em escalas do Sistema Solar. No entanto, para escalas galácticas, esta teoria foi pouco testada. Além disso, várias análises de dados de galáxias dependem do valor da constante de Hubble (H0), que está atualmente em discussão. Contudo, ao longo das décadas, muitas questões não resolvidas surgiram, e até o presente momento a RG não foi capaz de resolvê-las. Neste trabalho implementamos outro teste para a RG em escalas galácticas, combinando medidas de massa para uma galáxia elíptica que atua como lente gravitacional. Essas medidas podem ser obtidas por cinemática estelar e lentes gravitacionais, e são conectadas por um parâmetro γPPN, no formalismo Pós-Newtoniano Parametrizado. Este parâmetro, em nosso contexto, pode ser obtido a partir da razão de dois potenciais diferentes: o potencial Newtoniano Φ, que atua em partículas massivas e não relativísticas; e o potencial de curvatura Ψ, relacionado à curvatura do espaço-tempo, e mais importante para o movimento de partículas relativísticas e sem massa. Assumindo a RG, γPPN = 1. Essa abordagem foi implementada por Collett et al. (2018) usando um sistema cuja galáxia lente está em zl = 0.035, no qual eles encontram γPPN = 0.97 ± 0.09. Nós aplicamos essa mesma metodologia para o sistema SDP.81, no qual a galáxia lente está em zl = 0.299 e, portanto, muito mais distante do que o objeto estudado por Collett et al. Para isso, utilizamos dados provenientes de três instrumentos dos melhores observatórios da atualidade: ALMA, HST e VLT/MUSE. Além do teste de RG, fomos capazes de estudar a distribuição de massa da galáxia lente, e descobrimos que cerca de 45% de sua massa dentro de 1Re = 1.15600 é devido à presença de matéria escura descrita por um perfil Navarro-Frenk-White, estando nossa estimativa de acordo com estudos anteriores que utilizaram galáxias em redshift semelhante. No entanto, o resultado principal é a inferência de γPPN. Percebemos que nosso modelo mais provável indica um desvio da RG dentro de 1σ, mas com um erro estatístico muito pequeno, o que mostra que nossa inferência é dominada por erros sistemáticos. Estudos anteriores que restringiam γPPN com uma abordagem similar a nossa apresentam o mesmo problema. Usando a sistemática derivada desses estudos anteriores, fomos capazes de desenhar dois cenários possíveis. No pior cenário, os efeitos sistemáticos são da ordem de 25%, o que nos deixa com γPPN = 1.0092 ± 0.0001(stat) ± 0.2523(sys), que concorda com a RG dentro de 1σ. Já no melhor dos cenários, a sistemática é da ordem de 9% e a inferência final γPPN = 1.0092 ± 0.0001(stat) ± 0.0908(sys) ainda permanece em acordo com a RG, dentro de 1σ

Design considerations for future geodesy missions and for space laser interferometry

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Development towards a focus variation based micro-co-ordinate measuring machine

The increasing number of small and fragile parts that are being manufactured using micromachining technology has raised the demand for co-ordinate measurement machines (CMM) that can measure on a micro- and millimetric scale without contacting the part, thus avoiding damage to the surface of the part. These instruments are expected to measure on a micro- and millimetric scale with a measuring uncertainty in the nanometre range. A number of techniques used for contactless surface measurements exist, such as the focus variation (FV) technique, which have the ability to perform measurements on the micro- and millimetric scale in a short amount of time. These instruments may have the potential to be implemented in a non-contact micro-CMM platform. [Continues.

Cosmology and fundamental physics with the Euclid satellite

Euclid is a European Space Agency medium-class mission selected for launch in 2020 within the cosmic vision 2015–2025 program. The main goal of Euclid is to understand the origin of the accelerated expansion of the universe. Euclid will explore the expansion history of the universe and the evolution of cosmic structures by measuring shapes and red-shifts of galaxies as well as the distribution of clusters of galaxies over a large fraction of the sky. Although the main driver for Euclid is the nature of dark energy, Euclid science covers a vast range of topics, from cosmology to galaxy evolution to planetary research. In this review we focus on cosmology and fundamental physics, with a strong emphasis on science beyond the current standard models. We discuss five broad topics: dark energy and modified gravity, dark matter, initial conditions, basic assumptions and questions of methodology in the data analysis. This review has been planned and carried out within Euclid’s Theory Working Group and is meant to provide a guide to the scientific themes that will underlie the activity of the group during the preparation of the Euclid mission

Microfluidics and Nanofluidics Handbook

The Microfluidics and Nanofluidics Handbook: Two-Volume Set comprehensively captures the cross-disciplinary breadth of the fields of micro- and nanofluidics, which encompass the biological sciences, chemistry, physics and engineering applications. To fill the knowledge gap between engineering and the basic sciences, the editors pulled together key individuals, well known in their respective areas, to author chapters that help graduate students, scientists, and practicing engineers understand the overall area of microfluidics and nanofluidics. Topics covered include Finite Volume Method for Numerical Simulation Lattice Boltzmann Method and Its Applications in Microfluidics Microparticle and Nanoparticle Manipulation Methane Solubility Enhancement in Water Confined to Nanoscale Pores Volume Two: Fabrication, Implementation, and Applications focuses on topics related to experimental and numerical methods. It also covers fabrication and applications in a variety of areas, from aerospace to biological systems. Reflecting the inherent nature of microfluidics and nanofluidics, the book includes as much interdisciplinary knowledge as possible. It provides the fundamental science background for newcomers and advanced techniques and concepts for experienced researchers and professionals