Introdução: A doença arterial coronariana (DAC) persiste com alta morbimortalidade. Várias modalidades diagnósticas não-invasivas estão disponíveis para sua avaliação, incluindo escore de cálcio coronariano (EC), angiotomografia coronariana (AngioTC) e tomografia por emissão de pósitrons com rubídio (PET-CT82Rb), com ótimas sensibilidade e especificidade. A integração destes métodos em um exame híbrido permite delinear extensão anatômica e funcional da aterosclerose, possibilitando diagnósticos mais corretos. Objetivo: Avaliar anatomia coronariana e perfusão miocárdica de pacientes suspeitos ou portadores de DAC com tecnologia híbrida (PETCT82Rb e AngioTC/EC), testando a hipótese da maior acurácia do método híbrido em relação aos métodos isolados, correlacionando com desfecho de IAM/óbito cardíaco após 24 meses. Métodos: Foram incluídos 54 pacientes dos ambulatórios de cardiologia do Instituto do Coração (InCor-HCFMUSP), que realizaram estudo híbrido no departamento de Medicina Nuclear do InCor entre maio e outubro de 2013. A carga aterosclerótica coronariana foi contabilizada pelo escore de cálcio; a quantidade de lesões coronarianas, o grau de redução luminal e a composição das placas foram avaliados através da AngioTC; isquemia/fibrose pelo PET-CT82Rb foi contabilizada através do SDS (summed difference score) do estresse e repouso e a reserva de fluxo coronariana (RFC) foi considerada reduzida quando menor que 2mL/min/g. Após 24 meses, foi realizado contato telefônico e avaliação do prontuário dos pacientes, sendo pesquisado infarto agudo do miocárdio/óbito cardíaco como desfecho clínico principal. Resultados: Dentre os participantes, houve predomínio de homens (61,3%), com idade média de 55,5 ± 12,3 anos. A maioria apresentava sobrepeso/obesidade (76%), hipertensão arterial sistêmica (70,4%) e/ou dislipidemia (61,1%). O protocolo durou uma média de 52,2 ± 3,5 min e a dose total média de radiação foi 12,29 ± 2,88 mSv. A média do EC total foi 127,3 ± 249,0, sendo que 24% da amostra possuíam EC maior que 100. Houve predomínio de placas de ateroma mistas (51,3%), com 13% dos pacientes apresentando lesões angiograficamente significativas ( >= 50%). Oito pacientes apresentaram resultado alterado na análise perfusional qualitativa/semiquantitativa (14,8%), metade com isquemia e metade com fibrose. A RFC estava reduzida globalmente em 18,5% dos pacientes e de forma segmentar em 5,6%. Após 24 meses, 9,3% dos pacientes apresentaram infarto, 60% destes fatais. Houve concordância no máximo moderada dos métodos avaliados com a RFC (Kappa = 0,514; p= 0,001). Quanto ao desempenho dos métodos para ocorrência de IAM em 24 meses, foi demonstrada elevada acurácia da RFC para tal finalidade, com AUROC de 0,963 (IC95% 0,912 - 1,000; p= 0,001), com melhor ponto de corte de 1,975 mL/min/g. Não foi identificada alteração na sensibilidade ou no valor preditivo negativo quando a RFC foi agregada aos outros métodos, inclusive houve redução do valor preditivo positivo e da especificidade em relação à RFC isoladamente. Conclusão: O método híbrido não apresentou maior acurácia que a RFC pelo PET-CT82Rb isoladamente na predição de IAM em dois anos de acompanhamento, todavia, a tomografia cardíaca agrega informações importantes capazes de influenciar a conduta clínica nos pacientes não isquêmicos e possivelmente modifica desfechos em médio/longo prazo / Introduction: Coronary artery disease (CAD) persists with high morbidity and mortality. Several non-invasive diagnostic imaging modalities are available for its evaluation, including coronary calcium score (CS), coronary CT angiography (AngioCT) and positron emission tomography with rubidium (82Rb PET-CT), with excellent sensitivity and specificity. The integration of these methods into a hybrid examination allows delineating the anatomical and functional impact of atherosclerosis, enabling more accurate diagnoses. Objective: To evaluate coronary anatomy and myocardial perfusion of patients with suspected or known CAD with hybrid technology (82Rb PET-CT and AngioCT/CS), testing the hypothesis of the greater accuracy of the hybrid method in relation to the isolated methods, correlating with myocardial infarction/cardiac death outcome after 24 months. Methods: Fifty-four consecutive patients referred from the Cardiology outpatient clinics of the Heart Institute (InCor-HCFMUSP) to perform CAD assessment in a hybrid study in the Department of Nuclear Medicine of InCor, between May and October 2013, were enrolled. The coronary atherosclerotic burden was accounted by CS; the amount of coronary lesions, stenosis severity and plaque composition were evaluated through AngioCT; 82Rb PET-CT perfusional analysis was evaluated through the rest and dipyridamole stress summed difference score (SDS) and the coronary flow reserve (CFR) was considered impaired when < 2mL/min/g. After 24 months, the composite outcome of myocardial infarction and cardiac death was evaluated through telephone contact and patient\'s medical records. Results: From the 54 enrolled patients, mean age was 55.5 ± 12.3 years and 61% were male. Most patients presented overwheight/obesity (76%), systemic arterial hypertension (70%) and/or dyslipidemia (61%). The protocol lasted an average of 52.2 ± 3,5 min and mean radiation dose was 12.29 ± 2,88 mSv. The mean total CS was 127.3 ± 249.0, and 24% of the patients were above 100. There was a predominance of patients with mixed atheroma plaques (51.3%) and 13% presented angiographically significant lesions ( >= 50%). Eight patients presented perfusion impairment in the qualitative/semi-quantitative perfusion analysis (14.8%), half with ischemia and half with fibrosis. The CFR was globally reduced in 18.5% of the sample and in a segmental manner in 5.6%. After 24 months of follow-up, 9.3% of the patients had a myocardium infarction, 60% of these were fatal. A maximum of moderate agreement was found between the methods and CFR (Kappa = 0.514, p= 0.001). Regarding the performance of the different methods for predicting infarction in 24 months, CFR reached high accuracy, with AUROC of 0.963 (95% CI 0.912 - 1.0; p= 0.001), with a cutoff point of 1.975 mL/min/g. No variation in neither sensitivity nor negative predictive value was identified when the other methods were added to CFR, instead, there was a reduction in positive predictive value and specificity in relation to unaided CFR. Conclusion: There was no incremental value of the hybrid method when compared to isolated CFR 82Rb PET-CT for the prediction of myocardial infarction in two years follow-up. However, cardiac CT aggregates important information capable of influencing clinical management of nonischemic patients and possibly modifies medium/long-term cardiac outcomes

Um dos primeiros requisitos para utilização de lasers de diodo em espectroscopia é sua estabilização térmica. Neste trabalho desenvolvemos um sistema de controle de temperatura para laser de diodo que permite estabilização melhor que 0.01&#176C. O controle é feito através de um sistema sensor e um elemento Peltier como atuador. Lasers somente estabilizados em temperatura (estabilização primária) foram utilizados para realização de espectroscopia de vapores atômicos de Rb e Cs. / One of the first requisites for utilization of diode lasers in spectroscopy is its thermal stabilization. In this work, we develop a diode laser temperature controlling system, which yields stabilization better than 0.01&#176C. The controlling is obtained by means of a sensor system and a Peltier element as actuator. Lasers stabilized in temperature only (primary stabilizations) were utilized in the spectroscopy of atomic vapors of Rb and Cs.

Introdução: Na investigação não invasiva da doença arterial coronariana (DAC), destacam-se como métodos anatômicos de acurácia elevada a tomografia computadorizada (TC) para avaliação do Escore de Cálcio (EC) e a angiotomografia de coronárias (Angio-TC), e como método funcional a tomografia por emissão de pósitrons com Rubídio-82 (PET com 82Rb). As informações destes métodos se complementam e apresentam grande capacidade de ajudar na decisão terapêutica. Entretanto, muitas vezes, apenas um destes métodos está disponível na prática clínica, com destaque para a recente expansão da Angio-TC. Objetivos: Avaliar dois métodos diagnósticos não invasivos de referência quanto a análise anatômica e funcional coronariana e demonstrar a correlação entre a carga aterosclerótica pelo EC e o grau de obstrução coronariana pela Angio-TC com alterações de perfusão miocárdica através do PET com 82Rb. Material e Métodos: Estudo de corte transversal que incluiu 96 pacientes com suspeita de DAC significativa que realizaram PET com 82Rb sob estresse farmacológico no Departamento de Radiologia/Medicina Nuclear do InCor-HCFMUSP no período de junho a outubro de 2013, e que foram submetidos a Angio-TC dentro de até 30 dias. Placas coronarianas pela Angio-TC foram caracterizadas quando extensão, severidade e composição. Isquemia pelo PET com 82Rb foi definido como diferença entre os escores de estresse e repouso (SDS) maior ou igual a 2, e reserva de fluxo miocárdico (RFM) reduzido quando menor que 2. Resultados: Houve equilíbrio na distribuição do sexo (51% feminino), com média de idade de aproximadamente 59 anos. A hipertensão foi o fator de risco predominante (85%), seguida de dislipidemia (72%) e diabetes (35%). Angina foi o sintoma mais frequente (48%). As doses totais de radiação dos exames de TC foram relativamente baixas, sobretudo quando realizado no aparelho de 320 detectores (média de 2,79 mSv). A média do EC foi de 209,98 ± 488,68. O EC, principalmente quando maior que 400, teve forte associação com isquemia (razão de chances: 35,2; intervalo de confiança [IC] de 95%: 6,4 - 193,4). Estenose coronariana obstrutiva ( > 50%) pela Angio-TC também se correlacionou com maior risco de isquemia, especialmente quando a lesão detectada foi maior que 70% (razão de chances: 24,8; IC 95%: 7,6 - 80,3). Após ajustes para demais variáveis, tanto EC quanto estenose coronariana permaneceram associadas de forma independente. A combinação destas duas avaliações teve bom desempenho no diagnóstico de isquemia (área sobre a curva: 0,85; IC 95%: 0,74 - 0,95). Com relação à composição de placas, pacientes com RFM diminuída tiveram uma proporção significativamente maior de placas não-calcificadas e mistas do que aqueles com RFM preservada (p=0,006). Mais importante, estes tipos de composição de placa estiveram de forma independente associados com redução da RFM (razão de chances: 1,48; IC 95% 1,11 - 2,04). Conclusão: A Angio-TC e o EC se mostraram importantes preditores anatômicos, isolados e associados, na identificação de isquemia utilizando o PET com 82Rb como referência. Placas mistas e não-calcificadas se correlacionam com redução de RFM. Estas informações tem um importante papel na estratificação de risco cardiovascular de pacientes com DAC / Background: In the investigation of coronary artery disease (CAD), two highly accurate non-invasive methods play central roles, being the Coronary Computed Tomography (CTA) with Calcium Score (CS) the preferred exam for anatomical assessment, and Rubidium-82 PET-CT (82Rb PET/CT) for functional perfusional analysis. This information enables decision-making for clinicians on most settings, but unfortunately, only one of these exams is available on most medical centers, mostly CTA, which is now widely used worldwide. Objectives: To evaluate two reference non-invasive methods for CAD assessment, and demonstrate the correlation between plaque burden and anatomical stenosis degree, seen on CTA with CS, with the perfusional profile seen on 82Rb PET/CT. Methods: 96 individuals who performed 82Rb PET/CT for the evaluation of significant CAD at the Nuclear Medicine Department of the Heart Institute (InCor) of the University of Sao Paulo Medical School from June to October 2013 were included. CTA was performed during PET or scheduled during the next 30 days on a different scanner for the remaining patients. Coronary plaques on CTA/CS were then evaluated regarding extension, composition and flow-limiting stenosis degree. 82Rb PET/CT perfusion impairment was defined as present when rest and stress score difference (SDS) was >= 2, or when quantitative myocardial flow reserve (MFR) was under 2. Results: Mean age was 59 years old, and gender was balanced in the sample (female 51%). Hypertension was the most prevalent CAD risk factor (85%), followed by dyslipidemia (72%) and diabetes (35%). Chest pain was present in almost half the population (48%). Effective radiation exposure was low, especially when CTA was performed on the 320MDCT scanner (mean 2,79 mSv). Mean calcium score was 209,98 ± 488,68, demonstrating a strong association with ischemia, especially when above 400 (odds ratio: 35,2; 95% confidence interval [95%CI]: 6,4 - 193,4). Flow-limiting coronary stenosis (> 50%) seen on CTA also correlated with ischemia, especially when superior to 70% (odds ratio: 24,8; 95%CI: 7,6 - 80,3). After adjustment for other independent variables, either CS and CTA remained independently associated with ischemia. The combination of these two variables had a good performance for the detection of ischemia (area under curve: 0,85; 95%CI: 0,74 - 0,95). Regarding plaque composition, patients with mixed or noncalcified plaques were more likely to present decreased MFR (p=0,006). More importantly, these plaques were independently associated to reduced MFR (odds ratio: 1,48; 95%CI: 1,11 - 2,04). Conclusions: CTA and CS were important anatomical predictors of ischemia, either isolated or in association, using 82Rb PET/CT as reference. The presence of mixed or noncalcified plaques was significantly associated to decrease in MFR. These information are of emerging importance for DAC evaluation and management

What if an elementary particle such as an electron had an intrinsic electric dipole moment (EDM)? Existence of such an EDM would be an indication of time-reversal symmetry violation in the laws of Physics. The Standard model of Physics is considered incomplete, and theories that go beyond the standard model predict existence of such EDM’s within experimental reach. Experiments that search for their existence serve as a test bed for these theories. Use of laser-cooled Yb atoms launched in a fountain for EDM search has been proposed earlier. This thesis describes the main experimental work on generating a continuous cold beam of Yb atoms using laser cooling. Such cold beams are ideal for performing EDM experiments and have several advantages over the more common pulsed fountain. We demonstrate two ways to achieve this (i) extracting the beam from atoms trapped in 2- dimensions and (ii) deflecting the atomic beam using 1D-optical molasses. We find that the latter method gives a longitudinal temperature of 41 mK, which is a factor of 3 better than the former one. We also demonstrate the implementation of Ramsey’s separated oscillatory field technique in a thermal beam to measure the larmor precession frequency with high precision. This serves as a first step towards implementation with cold beam. Extending the work reported here, we suggest future experiment for measuring an EDM.

The deterministic generation and manipulation of quantum states has attracted much interest ever since the rise of quantum mechanics. Large-scale, distributed quantum states are the basis for novel applications such as quantum communication, quantum remote sensing, distributed quantum computing or quantum voting protocols. The necessary infrastructure will be provided by distributed quantum networks, allowing for quantum bit processing and storage at single nodes. Quantum states of light then allow for inter-node transmission of quantum information. Transmission losses in optical fibers may be overcome by quantum repeaters, the quantum equivalent of classical signal amplifiers. The fragility of quantum superposition states makes building such networks very challenging. Hybrid solutions combine the strengths of different physical systems: Efficient quantum memories can be realized using alkali atoms such as rubidium. Leading in the deterministic generation of single photons and polarization entangled photon pairs are semiconductor InAs/GaAs quantum dots grown by the Stranski-Krastanov method. Despite remarkable progress in the last twenty years, complex quantum optical protocols could not be realized due to low degree of entanglement, low brightness and broad wavelength distribution. In this work, an emerging family of epitaxially grown GaAs/AlGaAs quantum dots obtained by droplet etching and nanohole infilling is studied. Under pulsed resonant two-photon excitation, they emit single pairs of entangled photons with high purity and unprecedented degree of entanglement. Entanglement fidelities up to f = 0.94 are observed, which are only limited by the optical setup or a residual exciton fine structure. The samples exhibit a very narrow wavelength distribution at rubidium memory transitions. Strain tuning is applied via piezoelectric actuators to allow for reversible fine-tuning of the emission frequency. In a next step, active feedback is employed to stabilize the frequency of single photons emitted by two separate quantum dots to an atomic rubidium standard. The transmission of a rubidium-based Faraday filter serves as the error signal for frequency stabilization. A residual frequency deviation of < 30MHz is achieved, which is less than 1.5% of the quantum dot linewidth. Long-term stability is demonstrated by Hong-Ou-Mandel interference between photons from the two quantum dots. Their internal dephasing limits the expected visibility to V = 40%. For frequency-stabilized dots, V = (41 ± 5)% is observed as opposed to V = (31 ± 7)% for free-running emission. This technique reaches the maximally expected visibility for the given system and therefore facilitates quantum networks with indistinguishable photons from distributed sources. Based on the presented techniques and improved emission quality, pivotal quantum communication protocols can now be implemented with quantum dots, such as transferring entanglement between photon pairs. Embedding quantum dots in a dielectric antenna ensures a bright emission. For the first time, entanglement swapping between two pairs of photons emitted by a single quantum dot is realized. A joint Bell measurement heralds the successful generation of the Bell state Ψ+ with a fidelity of up to (0.81 ± 0.04). The state's nonlocal nature is confirmed by violating the CHSH-Bell inequality with S = (2.28 ± 0.13). The photon source is tuned into resonance with rubidium transitions, facilitating implementation of hybrid quantum repeaters. This work thus represents a major step forward for the application of semiconductor based entangled photon sources in real-world scenarios.

No description available.

The purpose of this work is to evaluate the ratio of the vector and axial vector coupling constants in the beta-decay of Rb^87. Particular attention is given to determining the sign of the ratio. All this is accomplished mainly by a conic analysis of the beta-spectrum and the calculation of a matrix element ratio. The results obtained indicate that the ratio of the coupling constants is negative. Due to uncertainties in nuclear matrix elements, only an approximate absolute value for the ratio can be secured. These results are consistent with other present evidence. / Thesis / Master of Science (MSc)

Light can exert optical forces on matter. In the macroscopic world these forces are minuscule, but on the microscopic or atomic scale, these forces are large enough to trap and manipulate particles. They may even be used to cool atoms to a fraction of a degree above absolute zero. This thesis details a number of experiments concerned with the optical manipulation of atoms and micron-size particles using free space light beams and photonic crystal fibres. Two atom guiding experiments are described. In the first experiment, a spatial light modulator is used to generate higher blue-detuned azimuthal Laguerre-Gaussian LG) beams, which are annular beams with a hollow core. These LG beams are then used to guide laser cooled rubidium-85 atoms within the dark core over a distance of 30 mm. The second atom guiding experiment involves attempting to guide laser cooled and thermal rubidium atoms through a hollow-core photonic crystal fibre using red-detuned light. Hollow-core photonic crystal fibres are fibres that are able to guide light with low attenuation within a hollow core. For this experiment a hot wire detection system was designed, along with a number of complex vacuum systems. The first dual-beam fibre trap for micron-size particles constructed using endlessly single-mode photonic crystal fibre (ESM-PCF) is described. The characteristics of dual-beam fibre traps are governed by the fibres used. As ESM-PCF has considerably different properties in comparison to conventional single- or multimode fibres, this dual beam ESM-PCF trap exhibits some novel characteristics. I show that the dual beam ESM-PCF trap can form trapping, repulsive and line potentials; an interference-free ‘white light’ trap; and a dual-wavelength optical conveyor belt.

Introdução: A avaliação e detecção precoce dos defeitos de perfusão miocárdica permite estratificar o risco cardiovascular e auxiliar a tomada de decisão terapêutica nos pacientes com DAC estabelecida ou suspeita. O PET/CT com Rb-82 na avaliação da perfusão e função miocárdica não invasiva é uma ferramenta de elevada acurácia diagnóstica. O presente trabalho procura estabelecer uma avaliação de performance de diagnóstica, entre dois métodos na medicina nuclear - SPECT com 99mTc-Sestamibi e PET/CT com Rb-82. Métodos: Avaliação da perfusão e da função do ventrículo esquerdo em 42 pacientes submetidos ao PET-CT com Rb-82 e SPECT com MIBI com mesmo estresse farmacológico (Dipiridamol), utilizando-se das variáveis de perfusão (SSS, SDS, SRS, fluxo sanguíneo e reserva coronariana) e de função (FEVE, DeltaFEVE, VDF, VSF - no repouso e no estresse), considerando o CATE como o método de referência. Resultados: No escore SDS, o Rb-82 apresentou valores médios próximos ao dobro do MIBI no grupo dos alterados (7,6 vs 3,9). Obteve-se um valor de sensibilidade do Rb-82 de 90,9%, com VPP de 88,2% (p=0,012) para o SSS e de 87,8%, com VPP de 87,8% (p= 0,012) para o SDS. As áreas sobre curva demonstraram superioridade do Rb-82 com maior exatidão e acurácia do método em relação ao MIBI na amostra avaliada. No escore de reversibilidade (SDS), houve maior sensibilidade em cut-off de menor valor e maior especificidade em cut-off de maior valor. FEVE em repouso e estresse, assim como, VDF e VSF em repouso e estresse apresentaram valores de concordância altos. Os valores de SSS, SRS e SDS apresentaram concordâncias moderadas. Houve aparente queda do DeltaFEVE no Rb-82, contudo similar tendência não foi observada no MIBI, considerando que as diferenças não foram significativas com relação ao número de vasos com estenose em ambos os radioisótopos (p > 0,05). Em outra análise, entre uma variável de função ventricular e a CFR global foi evidenciada diferença significativa (p=0,024) entre os grupos normal e alterado. No grupo alterado com CFR global < 2,0 houve redução do DeltaFEVE em 2,7%.Conclusão: O PET-CT com 82Rb apresenta maior exatidão e acurácia diagnóstica na avaliação perfusional miocárdica em relação ao SPECT com MIBI, inclusive com reclassificação dos grupos avaliados que passaram de defeito perfusional de pequena para moderada extensão. A FEVE estresse na população geral sugere valor mais alto no 82Rb (aquisição do exame no pico do estresse).Haveria uma sugestão de que no grupo com CATE alterado, a CFR global seria reduzida; que em maiores graus de estenose coronariana ao CATE, a CFR global decresceria; que existiria queda da DeltaFEVE no 82Rb quanto maior fosse o número de vasos obstruídos ao CATE. A relação entre a FEVE reserva e a CFR global no 82Rb foi significativa com queda da DeltaFEVE no grupo com CFR global alterada / Background: The evaluation and early detection of myocardial perfusion defects allows to stratify cardiovascular risk and it helps therapeutic decision-making in patients with established or suspected CAD. Rb-82 PET/CT in perfusion evaluation and noninvasive myocardial function is a tool of high diagnostic accuracy. The present study seeks to establish a diagnostic performance evaluation between two methods in nuclear medicine - 99mTc-Sestamibi SPECT and Rb-82 PET/CT. Methods: Evaluation of perfusion and left ventricular function in 42 patients submitted to Rb-82 PET-CT and MIBI SPECT with the same pharmacological stress (Dipyridamole), using perfusion variables (SSS, SDS, SRS, blood flow and coronary reserve) and function (LVEF, DeltaLVEF, EDV, ESV - in rest and stress), considering CAG as the reference method. Results: In the SDS score, Rb-82 presented mean values close to double the MIBI in the altered group (7.6 vs 3.9). A Rb-82 sensitivity of 90.9% was obtained, with PPV of 88.2% (p = 0.012) for SSS and 87.8% for PPV of 87.8% (p = 0.012) for or SDS. The areas on the curve indicated superiority of Rb-82 with greater accuracy and accuracy of the method in relation to the MIBI in the sample evaluated. In the reversibility score (SDS), there was greater sensitivity in the lower cut-off value and greater specificity in the higher cut-off value. LVEF at rest and stress, as well as VDF and VSF at rest and stress had high agreement values. The values of SSS, SRS and SDS presented moderate agreement. There was an apparent decrease of DeltaLVEF in Rb-82, however a similar trend was not observed in the MIBI, considering that the differences were not significant in relation to the number of vessels with stenosis in both radioisotopes (p > 0.05). In another analysis, a significant difference (p = 0.024) between the normal and altered groups was found of ventricular function variable and global CFR. In the altered group with global CFR < 2.0 there was a reduction of DeltaLVEF in 2.7%.Conclusion: 82Rb PET-CT has a greater accuracy and diagnostic accuracy of myocardial perfusion assessment in relation to MIBI SPECT, including reclassification of the evaluated groups that went from small to moderate perfusion defect extension. The LVEF stress in the general population suggests a higher value in 82Rb (acquisition of the exam at peak stress). There would be a suggestion that if the CAG group changed, the overall CFR would be reduced; in which greater degrees of coronary stenosis to CAG, the global CFR would decrease; and there would be a decrease of DeltaLVEF in 82Rb, the greater the number of vessels obstructed to CAG. The relation to reserve LVEF and overall CFR in 82Rb was significant with decrease in DeltaLVEF of the group with altered global CFR

Cette thèse est consacrée à l'étude expérimentale d'atomes piégés<br />et refroidis dans plusieurs types de structures lumineuses. Nous avons utilisé pour caractériser ces milieux des techniques de temps de vol, d'imagerie directe du nuage atomique et de spectroscopie pompe-sonde, afin d'obtenir des informations sur la température et la diffusion spatiale des atomes ainsi que sur leur mouvement dans les puits de potentiel.<br /><br />Nous avons d'abord étudié la dynamique d'atomes de césium dans des<br />réseaux optiques tri-dimensionnels brillants en présence d'un champ<br />magnétique, et nous avons en particulier montré que les réseaux optiques fonctionnant en régime sautant donnent lieu à un refroidissement et un piégeage efficaces, et qu'un mécanisme de rétrécissement par le mouvement y conduit à des raies vibrationnelles étroites sur les spectres de transmission pompe-sonde. Avec des atomes de césium, nous avons également créé et<br />caractérisé un réseau optique tri-dimensionnel brillant obtenu avec<br />seulement deux faisceaux laser grâce à l'effet Talbot, puis un milieu aléatoire engendré à partir d'un champ de tavelures.<br /><br />Enfin, nous avons étudié un ``moteur brownien'' pour des atomes de $^(87)$Rb dans un réseau gris asymétrique. Les résultats de l'étude<br />expérimentale sont en bon accord qualitatif avec des simulations numériques Monte-Carlo semi-classiques.