This thesis provides a summary of the laser system constructed in the Quantum Degenerate Gases Laboratory for laser cooling and trapping of 85/87Rband 6Li as well as of experiments that have been pursued in our lab to date. The first chapter provides an overview of the experimental focus of the QDG lab. The second and third chapters provide the fundamental theory behind laser cooling and trapping. The fourth chapter provides details of the laser system. The fifth chapter describes an experiment performed on the subject of dual-injection, performed in collaboration with Dr. James Booth of the British Columbia Institute of Technology (BCIT) involving the dual-injection of a single slave amplifier. The last chapter describes the progress made on the experimental setup needed for the study of Feshbach resonances between 85/87Rb and 6Li and the photoassociative formation of molecules.

This thesis provides a summary of the laser system constructed in the Quantum Degenerate Gases Laboratory for laser cooling and trapping of 85/87Rband 6Li as well as of experiments that have been pursued in our lab to date. The first chapter provides an overview of the experimental focus of the QDG lab. The second and third chapters provide the fundamental theory behind laser cooling and trapping. The fourth chapter provides details of the laser system. The fifth chapter describes an experiment performed on the subject of dual-injection, performed in collaboration with Dr. James Booth of the British Columbia Institute of Technology (BCIT) involving the dual-injection of a single slave amplifier. The last chapter describes the progress made on the experimental setup needed for the study of Feshbach resonances between 85/87Rb and 6Li and the photoassociative formation of molecules. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This thesis improves on the design of the Optical Trap Display (OTD), presented in 2018 [1]. Contributions include: real time animation; single beam, multiparticle suspension, point primitive anisotropic scattering, and virtual image approximation. First, real time animation was demonstrated on the OTD for the first time in full color at up to 30Hz refresh. Second, multi-particle systems allow for scaling of the display by a multiplicative factor, potentially up to orders of magnitude greater than the first OTD. Third, anisotropic scattering of point primitives was shown for individual suspended particles and multiple simultaneously suspended particles. Fourth, virtual images have been previously considered impossible in volumetric displays but by using perspective projections we have shown in simulation and experiment for the first time that an effect similar to a virtual image can be created.

Fluorescence lifetime imaging microscopy (FLIM) is a powerful technique to non-invasively map the physical and chemical environment within microfluidic devices. In this work FLIM has been used in conjunction with a variety of other techniques to provide a greater insight into flow behaviour and fluid properties at the microscale. The pH-sensitive fluorescent dyes, fluorescein and C-SNARF 1, have been used to generate pH maps of microfluidic devices with a time-gated camera and a time-and-space-correlated single photon counting (TSCSPC) detector, respectively. Using time-gated detection and fluorescein, the fluorescence lifetime images allow for direct reading of the pH. The relative contribution to fluorescence of the acid and basic forms of C-SNARF 1 was spatially resolved on the basis of pre-exponential factors, giving quantitative mapping of the pH in the microfluidic device. Three dimensional maps of solvent composition have been generated using 2-photon excitation FLIM (2PE-FLIM) in order to observe the importance of gravitational effects in microfluidic devices. Two fluidic systems have been studied: glycerol concentration in the microfluidic device was measured using Kiton red; water concentration in a methanolic solution was measured using ANS. The density mismatch between two solutions of different composition induced a rotation of the interface between two streams travelling side by side in a microchannel. The experiment has provided evidence of non-negligible gravitational effects in microflows. 2PE-FLIM has superior capability than methods used previously to assess similar phenomena. FLIM and micro-particle imaging velocimetry (μ-PIV) have been implemented on a custom-built open frame microscope and used simultaneously for multimodal mapping of fluid properties and flow characteristics. It has been shown that viscosity mismatch between two streams induces a non-constant advective transport across the channel and results in a flow profile that deviates from the usual Poiseuille profile, characteristic of pressure driven flow in microfluidic devices.

Ce travail de thèse est consacré à la manipulation et la déformation optique d'interfaces liquides molles, cela dans deux géométries fondamentales: plane et sphérique. Nous montrons alors que les déformations induites par pression de radiation optique permettent de déduire les propriétés des interfaces, comme la tension interfaciale par exemple. Dans le cadre de la déformation d'une interface liquide plane par pression de radiation, nous généralisons pour la première fois la manifestation électro-hydrodynamique des cônes de Taylor au régime optique, en montrant que des cônes liquides peuvent émerger sous fortes excitation laser. Nous avons alors caractérisé la morphologie de ces « cônes optiques » et nous montrons que l'angle de ces derniers dépend à la fois des paramètres de l'excitation laser mais aussi des caractéristiques des fluides. Une étude analytique ainsi qu'une étude numérique ont alors été menées afin de rendre compte des comportements observés.Afin d'étudier la déformation d'interfaces molles en géométrie sphérique, nous avons développé un double piège optique fibré en dispositif microfluidique dans une configuration inédite en termes de longueur d'onde excitatrice et de puissance laser. Nous avons alors appliqué notre dispositif à la déformation de vésicules en tant qu'objets modèles mous et nous montrons que notre double piège est bien adapté à la caractérisation rhéologique d'objets micrométriques déformables. Grâce à l'utilisation de faisceaux laser de forte puissance, nous mettons ici en évidence expérimentalement l'apparition d'un régime non-linéaire de déformation au sein de notre double piège optique. / This thesis work is devoted to the optical manipulation and deformation of soft liquid interfaces, in two fundamental geometries: plane and spherical. We then show that the deformations induced by optical radiation pressure allow to deduce the properties of interfaces, such as interfacial tension for example. In the framework of the deformation of a plane liquid interface by optical radiation pressure, we generalize for the first time the electro-hydrodynamic manifestation of Taylor cones to the optical regime, showing that liquid cones can emerge under intense laser excitation.We then characterized the morphology of these "optical cones" and we show that their angle depends both on the parameters of the laser excitation and on the characteristics of the fluids. An analytical study as well as a numerical investigation were then conducted to account for the observed behaviors. In order to study the deformation of soft interfaces in spherical geometry, we have developed a fiber-based dual-beam optical trap in a microfluidic device in a novel configuration in terms of excitation wavelength and laser power. We then applied our device to the deformation of vesicles as soft model objects and we show that our dual-beam trap is well adapted to the rheological characterization of deformable micron-sized objects. Thanks to the use of high laser power beams, we experimentally highlight the appearance of a non-linear deformation regime within our double optical trap.

Neste trabalho demonstramos o confinamento de átomos de sódio usando a armadilha magneto-óptica, onde os átomos foram capturados diretamente a partir da distribuição inicial do vapor atômico a uma temperatura ambiente, contido em uma célula fechada. Observamos além da nuvem de átomos aprisionados, estruturas circulares em forma de anek, que surgem devido ao desalinhamento introduzido nos feixes de aprisionamento. Estudamos o comportamento do raio do anel em função de vários parâmetros utilizados na armadilha magneto-óptica como por exemplo: gradiente de campo magnético, intensidade do laser, dessintonia e desalinhamento. Os experimentos foram realizados no regime de baixa densidade (N<10s) onde o raio do anel é independente do número de átomos aprisionados. Assim, os resultados obtidos podem ser explicados utilizando um modelo simples que leva em conta a força de vórtice dependente da coordenada radial (ou macroscópica) e as forças usuais presentes na armadilha magneto-óptica / In this work we demonstrate the confinement of neutral sodium atoms using the magneto-optical trap, where the atoms were captured directly from the low velocity tail of the room-temperature atomic vapor contained in the closed vacuum cell. We observed besides the cloud shaped, circular structures like a ring of trapped atoms that apeears when we introduce a misalignment among the trapping beams. We studied the behavior of ring radius with respect to several trapping parameters as: magnetic-field gradient, laser intensity, detuning, and misalignment. The experiments were performed in the low density regime (N<10s), so the ring radius is independent of the number of trapped atoms. Hence, the results obtained can be explained using a simple model that takes into account a radial coordinate dependent (or macroscopic) vortex force and the usual magneto-optical trap forces

Observamos neste trabalho o processo de mudança de estrutura fina em colisões entre átomos de 85Rb resfriados e aprisionados em uma armadilha magneto-óptica. Medimos, através da fotoionização de fragmentos atômicos gerados nessas colisões, as taxas segundo as quais os átomos deixam a armadilha induzidos por esse processo colisional. Realizamos estudos das taxas de perda com relação a intensidade do laser de aprisionamento e com a freqüência, utilizando para isso a técnica de catálise. Nossos resultados indicam que a contribuição do processo de mudança de estrutura fina para a taxa de perdas total não é dominante. Constatamos que a estrutura hiperfina desempenha um papel importante na dinâmica colisional e na determinação dos valores das taxas. Interpretamos nossos resultados através de um modelo semi-clássico, sendo que este foi incapaz de explicar todos os efeitos observados. Propusemos algumas explicações qualitativas para as discrepâncias observadas. Acreditamos que nossos resultados devam servir de estímulo para novos trabalhos teóricos nesta área. / We report the observation of trap-loss collisional rates due to fine structure changing collisions between cold and trapped 85Rb atoms. We have measured, by photoionization of the atomic fragments in 5P1/2 state originated in these collisions, the rates through the atoms leave the trap induced by this loss mechanism. We carried out experiments to determine the rate dependence with the intensity of the trapping laser, and with the frequency, using the catalisys technique. We also measured the contribution of this process to the total trap-loss rate and determined that fine structure changing is not the dominant loss mechanism. It was also observed that the hyperfine structure plays an important role in the rate behavior. We compared our results with those given by a semiclassical theoretical approach, the Gallagher-Pritchard model, and some disagreements were observed. We proposed some arguments to explain these discrepancies. We believe that such results should stimulate theoretical work on this field.

Neste trabalho é apresentada a construção da montagem de um sistema experimental para resfriar átomos de estrôncio. A construção do sistema está focada no estudo do espalhamento coletivo em nuvens atômicas frias e ultrafrias por meio da teoria de Mie. O estrôncio é um elemento que conta com dois estágios de resfriamento, o primeiro utilizando a transição forte entre estados singletos &sup1;S&#8320;-&sup1;P &#8321; de &Gamma; = (2 &pi;)32 MHz, e o segundo com uma transição fraca entre estados singleto e tripleto &sup1;S&#8320;-&sup3;P&#8321; de &Gamma; = (2 &pi;)7,5 MHz. O objetivo deste trabalho é a construção do sistema para resfriar átomos de estrôncio utilizando a primeira transição. A construção do sistema se apresenta em várias partes, primeiro a construção do um forno como fonte de vapor de estrôncio, onde o estrôncio metálico é aquecido até uma temperatura T = 600&deg;C. O forno conta com um sistema de microtubos encarregados de colimar o feixe atômico, estes microtubos tem um diâmetro interno D &asymp; 180&micro;m e um comprimento de 8mm. Depois da implementação do forno e do sistema de microtubos foi medido o perfil de velocidades transversais e a divergência do feixe atômico que sai do forno. A largura tem um valor wr = (2&pi;)108 MHze a divergência do feixe de &alpha; &asymp;4,12. A segunda parte do sistema conta com a construção do desacelerador Zeeman, responsável por desacelerar os átomos do feixe atômico utilizando um feixe laser contrapropagante de &lambda;=461 nm, circularmente polarizado e com uma dessintonização utilizada, após a caracterização do sistema, de &Delta;=(-2&pi;)580MHz. Os átomos sentiram os efeitos da força de pressão radiativa dentro de um tubo de comprimento de 0,28m. Para compensar o efeito Doppler causado pelo movimento dos átomos foi utilizado um arranjo de bobinas em configuração spin flip para gerar o campo. A terceira e principal parte do sistema foi a construção da armadilha magnetoóptica (AMO). Onde os átomos que saem do desacelerador Zeeman são confinados e resfriados pela combinação de seis feixes contrapropagantes, dos quais três são retrorefletidos utilizando a transição &Gamma;=(2&pi;)32MHz. A dessintonia dos feixes após da caracterização do sistema foi de &Delta;=(-2&pi;)39MHz. Depois da construção do sistema foi feita a primeira caracterição da armadilha magneto-óptica de átomos de estrôncio 88 em nosso grupo, onde obtivemos a temperatura dos átomos na armadilha para o eixo vertical da expansão foi de Tv=4.7mK e para o eixo horizontal de TH=4mK. Também foi medido o tempo de carga dos átomos na armadilha tcarga=0.15s como bombeamento óptico de estado &sup3;P&#8322;-&sup3;D&#8322;. O tempo de vida foi de 0.3s e 0.03s com e sem bombeamento óptico, respectivamente. / This work presents the construction of the assembly of an experimental system for cooling strontium atoms. The construction of the system is focused on the collective scattering in atomic cold cloud and ultra cold using the Mie theory. The strontium is an element that permits two stage of cooling, the first using the strong transition between singlet states &sup1;S&#8320;-&sup1;P&#8321; of &Gamma;=(2&pi;) 32 MHz, and a second stages is the weak transition between singlet and triplet states &sup1;S&#8320;-&sup3;P&#8321; de &Gamma;=(2&pi;) 7.5MHz. The objective of this work is building the system for cooling strontium atoms using the first transition. The construction of the system is presented in several parts. First is described the construction of oven as vapor source strontium, where the strontium metal is heated to Temperature Range T = 600&deg;C. The oven has a microtubule system responsible for collimating the atomic beam, these microtubules has an internal diameter of D &asymp; 180&micro;m and a length of 8mm. After implementation of the oven system and the microtubes were measured transverse velocity profile and the divergence of the atomic beam that leaves the oven, the width value was f wr=(2&pi;)108MHzand beam divergence value was &alpha; &asymp; 4,12. The second part of the system relies on the construction of the Zeeman slower responsible for decelerating the atoms of the atomic beam using a laser beam antipropagating of &lambda; = 461 nm nm with a circularly polarized , the detuning used after of the characterization of the system was &Delta; = (2&pi;)580 MHz. Atoms felt the effects of pressure force radiative within a tube length of 0.28m to compensate the Doppler shift due to motion a of atoms used an arrangement of coils in configuration \"spin flip\" to generate the magnetic field to compensate this effect. The third and main part of the system was the construction of magneto-optical trap (MOT), the atoms coming out of the Zeeman decelerator are confined and cooled by a combination of six counterpropagating beams, three of which are retro reflected using the transition &Gamma; = (2&pi;)32MHz, the detuning of the beam after the characterization of the system was &Delta; = (-2&pi;) 39 MHz and the opposite polarization for each pair of beam in the same direction. After the construction of the system was made the first magneto-optical trap of strontium atoms 88, the temperature of the trap was atoms to the vertical he expansion was Tv = 4.7mK and the horizontal axis TH = 4 mK 4, also was measured loading time of the atoms in the trap tcharge = 0.15s as optical pumping state &sup3;P&#8322;- &sup3;D&#8322;. The lifetime with and without optical pumping was tlife = 0.3s and tlife = 0.03s respectively.

Neste trabalho estudamos a absorção cooperativa de dois fótons em processos de colisão entre átomos frios de sódio aprisionados. Efeitos não-lineares exigem amostras de alta densidade para ser observados. Redesenhamos nosso sistema experimental para conseguir amostras de 1012 átomos/cm3. As principais alterações foram a construção de um desacelerador Zeeman em configuração spin-flip, a implementação de bombeamento diferencial entre o forno e a câmara principal, assim como redesenhar o forno. A fim de compreender e melhorar os processos de medição utilizamos a técnica de fotoionização nos estados 32P1/2 e 32P3/2. Com esses dados conseguimos calcular a seção transversal de ionização para cada um desses estados, que está de acordo com valores reportados na literatura. Estes resultados mostram que o novo desenho do sistema permite um grande ponto de partida para a medição da absorção de dois fótons. Uma tentativa de medir a absorção de dois fótons foi feita. Um pequeno aumento no número de íons produzidos por unidade de tempo foi observada em uma região deslocada para o vermelho de cerca de 4,5 GHz de onde inicialmente se esperava ocorrer a transição. Isto motiva a aprofundar o estudo da absorção de dois fótons, já que provavelmente essa medida seja um indício da ocorrência desse fenômeno. Assim, tanto a medição da seção de choque dos estados 32P1/2 e 32P3/2 e a tentativa de medir a absorção de dois fótons, fornecem uma base sólida para conhecer qual é a melhor maneira de obter resultados mais decisivos no que diz respeito à absorção cooperativa de dois fótons, e as vantagens do nosso sistema em futuros experimentos. / In this work we study the cooperative two-photon absorption in collisional processes between cold trapped sodium atoms. Nonlinear effects require high density samples to be observed. We redesign our experimental system to achieve samples up to 1012 atoms/ cm3 .The key changes were building a spin-flip Zeeman slower, implementing differential pumping between the oven and the chamber and changing the oven´s design. In order to understand and improve the measurement processes we did photoionization from the states 32P1/2 e 32P3/2. With this data we could calculate the ionization cross section for each of these states, which is in agreement with values reported in the literature. These results show that the new design of the system allows a great starting point for measuring of two-photon absorption. An attempt to measure the absorption of two-photon was made. A small increase in the number of ions produced per unit time was observed in a region shifted to the red of about 4.5 GHz from where we initially expected the transition to occur. This probably indicates two-photon absorption. Thus, both the measurement of cross section of states and the attempt to measure the absorption of two photons, provide a solid foundation for understanding what is the best way to obtain more decisive results with regard to cooperative absorption, and the advantages of performance of our system in future experiments.

Dentro as técnicas de controle do movimento atômico utilizando pressão de radiação, aprisionamento tem merecido maior destaque por produzir amostras de átomos mais frios (temperaturas da ordem de &#956K), com altas densidades e confinadas em pequenas regiões do espaço. Devido a essas motivações, tem sido grande o esforço para desenvolver e caracterizar estas armadilhas atômicas. Uma das mais eficientes armadilhas de átomos neutros construídas até agora é a armadilha magneto-óptica. O átomo uma vez capturado por este tipo de armadilha passa por um intenso processo de desaceleração via efeito Doppler e acaba por ficar confinado no poço de potencial gerado pela interação com o campo magnético. O número e a densidade de átomos aprisionados, o tamanho da nuvem e o processo de carga possuem forte dependência com os parâmetros da armadilha, tais como: Este trabalho trata da caracterização de uma armadilha deste tipo para átomos de sódio através de um estudo sistemático para descobrir as condições de sua melhor performance. Paralelamente a este estudo, desenvolvemos modelos teóricos para entender em detalhe os processos de produção dessas nuvens de átomos aprisionados e as forças envolvidas neste tipo de material que é esse gás super resfriado. / Among the various atomic motion control techniques using radiation pressure magneto-optic trapping has been looked at with great enthusiasm because it produces samples of cold atoms (temperatures about &#956K), with high densities and confined in small regions of space. Due to these motivations the efforts for developing and characterizing these atoms traps has been high. Once the atom is captured by the magneto-optic trap, it goes through an intense process of desacceleration via Doppler Effect and ends up confined in the potential well genered by the interaction with the magnetically Field. The number and the density of the trapped atoms, the size of the cloud and the loading process are strongly related to trap parameters, such as: magnetic Field gradient, laser beam intensity and background vapor temperature. This work deals with the characterization of a trap of this kind for sodium atoms through a systematic study, in order to discover the conditions for a better performance. At the same time theoretical models are developed in order to understand in depth the atomic forces involved in the production of a new kind of material which is this highly refrigerated gas.