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In this dissertation I present experimental results obtained on the mercury optical clock project in the research group of Jason Jones at the University of Arizona. The project began in 2008 with the purpose of investigating the feasibility of neutral mercury as an optical clock species. The first series of investigations involved building the essential apparatus and scanning the doppler-broadened 6¹S₀ - 6³P₀ clock transition in ¹⁹⁹Hg. Here I present significant modifications to the cooling and trapping laser, improvements to the spectroscopy laser linewidth, and attempts to measure the 2-photon transition in ¹⁹⁹Hg. After previously demonstrating spectroscopy of the mercury clock transition using an optically-pumped semiconductor laser for the cooling and trapping source (OPSL), we replaced the OPSL with a a fiber-amplified ECLD system. We custom built a fiber amplifier to provide gain at 1015 nm, demonstrating the system can yield up to 5 W of signal power with excellent suppression of the ASE power. We find that the ASE is well suppressed by using a two-stage configuration and short sections of gain fiber. The linewidth of our original spectroscopy laser was over 10 kHz, which is unsuitable to resolve of sub-Doppler features. To enhance the performance of our spectroscopy system, we integrated faster feedback bandwidth using AOMs, and incorporated derivative gain into the system. This resulted in a feedback bandwidth for our spectroscopy laser of over 200 kHz. With this system, we demonstrate anactively stabilized linewidth of 525 Hz for our spectroscopy system. Using the upgraded cooling and spectroscopy laser systems, we demonstrate spectroscopy of the clock system and confirm temperature measurements derived from the transition linewidth. We also describe attempts to detect the recoil shift and 2-photon transition in neutral mercury.

[pt] Neste trabalho estudamos a aplicação da metodologia de Box & Jenkins em séries de diferenças entre relógios de precisão a fim de definir qual o intervalo ótimo entre calibrações. Para tanto, utilizamos um conjunto de procedimentos que permite a automatização desta metodologia até um grau em que não é mais necessária a intervenção humana. Propomos o uso da análise de variância para definir a ordem da diferenciação necessária a cada série, o uso da Função de Autocorrelação Estendida para definir os hiperparâmetros do modelo, o uso do método de Mínimos Quadrados Ponderados Recursivos para obtenção dos parâmetros do modelo além de alguns testes para validação do modelo encontrado. Utilizamos os dados reais obtidos dos relógios do Observatório Nacional - Departamento da Hora, Laboratório Primário de Tempo e Frequência para mostrar que a metodologia, como proposta, é válida. / [en] In this work we study the application of the Box & Jenlins methodology to series of differences between precision clocks to define what is the best interval between calibratons. We use an ensemble of preceedings that allows the automatizion of this methodology to a level where there are no more need of human´s intervention. We propose the use of variance analysis to define the order of differentiation necessary to each series, the use of Extended Autocorrelation Function to define the model´s hiperparameters, the use of Recursive Pondered Least Square to obtain the model´s parameters and some tests to validate the resulting model. We use data from clocks of the National Observatory - Hour Department, Frequency and Time Primary Laboratory to show that the proposed methodology is valid.

The concept of time in physics underwent significant changes in the decades following World War II. This dissertation considers several ways in which American physicists grappled with these changes, analyzing the extent to which philosophical methods and questions played a role in physicists' engagement with time. Two lines of questioning run through the dissertation. The first asks about the professional identities of postwar American physicists in relation to philosophy, as exemplified by their engagement with the concept of time. The second analyzes the heterogeneous nature of time in physics, and the range of presuppositions and assumptions that have constituted this "fundamental" physical concept. The first chapter looks to the development of atomic clocks and atomic time standards from 1948-1958, and the ways in which new timekeeping technologies placed concepts such as “clock”, “second,” and “measure of time” in a state of flux. The second chapter looks to the experimental discovery of CP violation by particle physicists in the early 1960s, raising questions about nature of time understood as the variable “t” in the equations of quantum mechanics. The third chapter considers attempts to unify quantum mechanics and general relativity in the late 1960s, which prompted physicists to question the “existence” of time in relation to the universe as a whole. In each episode considered, physicists engaged with the concept of time in a variety of ways, revealing a multiplicity of relationships between physics, philosophy, and time. Further, in each case physicists brought a unique set of assumptions to their concepts of time, revealing the variety ways in which fundamental conceptsfunctioned and changed in late twentieth century physics. The result is a heterogeneous picture of the practice of physics, as well as one of physics’ most basic concepts. / History of Science

The advent of laser cooling and optical manipulation for atomic samples revolutionized atomic physics in 1990’s, allowing the creation of new phases of matter, more accurate atomic clocks, and enabling leading candidates for the first functional quantum computer. This could not have been predicted at the time, and is a testament to the value of fundamental research for its own sake. These same laser cooling techniques are now being applied to simple molecular systems with the same revolutionary potential. In this thesis, I will present a range of experiments exploring these schemes in a new class of molecules, the diatomic alkaline earth hydrides. We present the creation and characterization of a bright beam of cold barium hydride molecules, high precision spectroscopy of these samples, as well as optical deflection and transverse cooling. This represents the first laser cooling of a Hydride molecule. This is a crucial step towards the creation of new cold molecular samples for a variety of scientific applications. In the final chapter, I will change gears, and introduce new ideas for the detection of scalar field dark matter. While this variety of dark matter is typically searched for using atomic clocks, I will show that the same coupling also leads to anomalous acceleration of test masses. This acceleration would be detectable using both a network of precision acceleration sensors known as the IGETS network, and by the LIGO observatory. This new technique will compliment existing search strategies, and has higher sensitivity for a wide region of parameter space.

The immaculate control of atoms and molecules with light is the defining trait of modern experiments in ultracold physics. The rich internal degrees of freedom afforded by molecules enrich the toolbox of precision spectroscopy for fundamental physics, and hold great promise for applications in quantum simulation and quantum information science. A vibrational molecular lattice clock with systematic fractional uncertainty at the 14th decimal place is demonstrated for the first time, matching the performance of the earliest optical atomic clocks. Van der Waals dimers of strontium are created at ultracold temperatures and levitated by an optical standing wave, whose wavelength is finely tuned to preserve the delicate molecular vibrational coherence. Guided by quantum chemistry theory refined by highly accurate frequency-comb-assisted laser spectroscopy, record-long Rabi oscillations were demonstrated between vibrational molecular states that span the entire depth of the ground molecular potential. Enabled by the narrow molecular clock linewidth, hertz-level frequency shifts were resolved, facilitating the first characterization of molecular hyperpolarizability in this context. In a parallel effort, deeply bound strontium dimers are coherently created using the technique of stimulated Raman adiabatic passage. Ultracold collisions of alkaline-earth metal molecules in the absolute ground state are studied for the first time, revealing inelastic losses at the universal rate. This thesis reports one of the most accurate measurement of a molecule's vibrational transition frequency to date, which may potentially serve as a secondary representation of the SI unit of time in the terahertz (THz) band where standards are scarce. The prototypical molecular clock lays the important groundwork for future explorations into THz metrology, quantum chemistry, and fundamental interactions at atomic length scales.

[pt] Neste trabalho nós procuramos uma solução para o problema: como construir uma escala de tempo atômico baseada em um pequeno grupo de relógios atômicos? Nós geramos uma escala de tempo atômico independente a partir de um conjunto de relógios atômicos, chamada ETAB1(onrj). Nós propomos que a ETAB1(ONRJ) seja usada como referência para a geração de um o novo Tempo Universal Coordenado Brasileiro, chamado de TUC(ONRJ) proposto. Nós mostramos que o TUC(ONRJ) proposto será mantido coordenado com o TUC(BIPM) dentro dos limites recomendados pelo Comité Consultatif pour la Définition de la Seconde, isto é, a diferença entre TUC e TUC(ONRJ) proposto, menor que mais ou menos 100ns. Para menter a Hora Legal Brasileira (TUC(ONRJ)) coordenada com a Hora Mundial (TUC(BIPM) é necessário realizar a rastreabilidade internacional da grandeza tempo. Um método é proposto para obtenção de uma estimativa diária da posição do TUC(ONRJ) utilizando o filtro de Kalman e um receptor GPS, com uma incerteza de mais ou menos 35ns. Uma comparação do desempenho entre as escalas de tempo TUC (ONRJ) proposto, TUC(NIST) e TUC(USNO) é apresentada / [en] In the present work we look we look for a solution of the problem: how to construction na atomic time scale based in a smallgroup of atomic clocks. We generate an independent atomic time scale from an ensemble of atomic clocks, named ETAB 1 (ONRJ). We propose that ETAB 1(ONRJ) be used as a reference for the generation of a new Brazilian Coordinated Universal Time, named UTC (ONRJ)proposed. We show that the UTC (ONRJ)proposed will be maintained coordinated with UTC (BIPM) within the limitis recommended by the Comité consultatif pour la Définition de la Seconde, that is, the difference between UTC (BIMP) and UTC (ONRJ)proposed less than +/-100ns. To maintain the UTC (onrj) coordinated with UTC(BIPM) it is necessary to realize the international traceability of time quantity. A method is proposed for obtain ddaily estimates of UTC (ONRJ) - UTC(BIPM) using Kalman filter and GPS receiver with uncertainty of +/-35ns. A comparison of performance between the time scales UTC(ONRJ)proposed, UTC(NIST) and UTC(USNO) is presented.

For years, frequency standards have been the cornerstone of precision measurement. Among these frequency standards, atomic clocks have set records in both precision and accuracy, and have redefined the second. There is growing interest in more complex molecular systems to complement precision measurements with atoms. The rich internal structure of even the simplest diatomic molecules could provide new avenues for fundamental physics research, including searches for extensions to the Standard Model, dark matter candidates, novel forces or corrections to gravity at short distances, and tests of the variation of fundamental constants. In this thesis, we discuss the fundamental architecture for a precise molecular system based on a strongly forbidden weakly-bound to deeply-bound vibrational transition in 88Sr dimers. We discuss early studies to characterise our system and gain technical and quantum control over the experiment in anticipation of a precise metrological measurement. We, then, demonstrate a record-breaking precision for our 88Sr2 molecular clock ushering in a new era for precision measurement with clocks. Borrowing techniques from previous atomic clock architecture, we measure a ∼32 THz clock transition between two vibrational levels in the electronic ground state, achieving a fractional uncertainty of 4.6 × 10−14 in a new frequency regime. In this current iteration, our molecular clock is fundamentally limited by two-body loss lifetimes of 200 ms and light scattering induced by our high-intensity lattice. Given these limitations, we suggest improvements to combat the effects from both the lattice and two-body collisions in our 1D trap. These include technical improvements to our experiment and strategic choices of particular clock states in our ground electronic potential. We describe in-depth studies of the chemistry and polarizability behaviour of our molecule, which elucidates preferential future directions for a second generation clock system. These empirical results are substantiated by an improved theoretical picture. Ultimately, our molecular system is built in order to probe new physics and as a tool for precision measurement. Leveraging our record-precision clock and our new-found understanding of our molecule, we predict the capacity for our system to place meaningful, competitive constraints on new physics, in particular on Yukawa-type extensions to gravity. These predictions motivate improvements to our current generation clock and set the stage for future measurements with this system.

Les horloges atomiques miniatures présentent des stabilités de fréquence inégalées avec des volumes de quelquescentimètres cubes et des consommations inférieures à 100mW.Dans cette thèse, les paramètres optimaux concernant la conception et la fabrication des cellules à vapeur decésium, un des composant clés de ce type d’horloges, sont définis. Ainsi, les performances de plusieurs cellulesont été caractérisées en condition d’horloge à court et long terme. En parallèle, des solutions sont proposéespour pallier à certaines limitations telles que la plage de température opérationnelle, le coût de fabrication dudispositif et la facilité d’assemblage du module physique.Un nouveau mélange de gaz tampon composé de néon et d’hélium peut étendre la plage de fonctionnementau-dessus de 80 C, en adéquation avec les besoins industriels. A l’inverse des gaz tampon usuels, ce mélangeest compatible avec les dispensers de césium solides, dont la fiabilité est établie.Outre les gaz tampon, les revêtements permettent également de limiter la relaxation induite par les parois dela cellule. Ici, des revêtements d’octadécyltrichlorosilane sont étudiés. Un effet anti-relaxant a été observé dansdes cellules centimétriques et un procédé a été développé pour revêtir des cellules micro-fabriquées.D’autres sources de césium sont présentées pour s’affranchir des inconvénients propres aux dispensers solides.Un dispenser sous forme de pâte, qui peut être déposée collectivement, a été étudié et montre des densitésatomiques stables jusqu’à présent. Un concept de vannes hermétiques micro-fabriquées a été proposé poursceller hermétiquement et séparer des cellules d’un réservoir de césium commun.Les premières étapes vers un module physique micro-fabriqué sont ensuite présentées. En particulier, un designoriginal de cellule combinant des réseaux de diffraction à une cavité en silicium formée par gravure anisotropea été caractérisé et a montré des contrastes CPT remarquables malgré un volume de cavité réduit, ce qui permettraitde réaliser un module physique particulièrement compact. Enfin, des cellules intégrant des résistanceschauffantes et thermométriques ont été fabriquées et leur compatibilité vis-à-vis du champ magnétique généréa été caractérisée dans un prototype de module physique compact. / Chip-scale atomic clocks (CSACs) provide unprecedented frequency stability within volumes down to a fewcubic centimeters and power consumptions as low as 100mW.In this work, we determine the optimal parameters regarding the design and the fabrication of cesium vaporcells, one of the key components of a CSAC. For this purpose, cells were characterized on both short and longtermperformances in clock setups. In addition, we propose solutions to overcome present limitations includingthe operating temperature range, the device microfabrication cost and the ease of integration of the physicspackage.A novel mixture of buffer-gas composed of neon and helium was found to potentially extend the operating rangeof the device above 80 C, meeting the industrial requirements. Unlike the well-known buffer gas compositions,this mixture is compatible with solid cesium dispensers whose reliability is established. As an alternativeto buffer gases, wall coatings are known to limit the relaxation induced by sidewalls. Here, we investigatedoctadecyltrichlorosilane (OTS) coatings. An anti-relaxation effect has been observed in centimeter-scale cellsand a process was developed to coat microfabricated cells.Other cesium sources have been investigated to overcome the drawbacks imposed by solid cesium dispensers. Apaste-like dispenser, which can be deposited collectively, was explored and has shown stable atomic densities sofar. Single-use zero-leak micro valves were also proposed to hermetically seal and detach cells from a commoncesium reservoir.Eventually, the first steps toward a microfabricated physics package were made. In particular, an originalcell design combining diffraction gratings with an anisotropically etched single-crystalline silicon sidewalls wascharacterized and exhibited remarkable CPT contrasts despite a reduced cavity volume, which could lead to amore compact physics package. Finally, cells with integrated heating and temperature sensing resistors werefabricated and their magnetic field compliance was characterized in a compact physics package prototype.

Orientadores: Flavio Caldas Da Cruz, Luiz Eduardo Evangelista de Araujo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-28T03:18:42Z (GMT). No. of bitstreams: 1 LamillaRubio_ErickAbraham_M.pdf: 5773132 bytes, checksum: 33effe596fdd1deb74be96f588fc6150 (MD5) Previous issue date: 2015 / Resumo: Neste trabalho foi feito um estudo experimental da transmissão de padrões de frequência atómicos através de uma rede de fibra optica. Até onde sabemos este tipo de transmissão foi realizada pela primeira vez no Brasil. Utilizamos uma conexão de fibra óptica entre o Instituto de Física Gleb Wataghin (IFGW) e a Faculdade de Engenharia Elétrica e Computação (FEEC) da UNICAMP, correspondendo a uma distância de aproximadamente 2 km, e um comprimento total de fibra de 18 km. Frequências de RF derivadas de padrões de frequência de Rubídio e de um receptor GPS foram transmitidas e caracterizadas através de medidas de frequência, particularmente por gráficos de variância de Allan, e medidas da fase / Abstract: In this experimental work, transmission of an atomic frequency standard through an optical fiber network has been implemented for first time in Brazil, to the best of our knowledge. We have used a fiber link between the Institute of Physics (IFGW) and the Department of Electrical Engineering inside the campus of the University of Campinas (UNICAMP) corresponding to 18 km fiber link (2km between buildings). Radio frequencies derived from a Rubidium standard and a GPS (Global Position system) receiver has been transmitted and characterized via phase and frequency measurements, particularly trough Allan deviation plots and phase measurements / Mestrado / Física / Mestre em Física / 2013/15492-2 / FAPESP