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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.

Este trabalho tem como objetivo principal desenvolver uma nova fonte de laser de diodo compacta e robusta, além de um novo drive de controle para serem utilizados em padrões primário de tempo e frequência tipo chafariz de átomo de Césio e padrões compacto baseados em átomos frios. Um dos requisitos para utilização de laser de diodo em padrões primários de tempo e frequência é sua estabilidade em frequência e baixíssimo ruído espectral. Além disto, dada à aplicação embarcada, o laser deve ser extremamente robusto com relação às condições adversas: mecânicas, térmicas e elétricas. Tanto a parte optomecânica, quanto os controles eletrônicos do novo laser foram desenvolvidos neste trabalho. Vale salientar que tal sistema, em sua concepção, é de grande interesse para diversos outros tipos de aplicação, como espectroscopia de gases (LIDAR), referências em outras frequências e experimentos de física atômica e molecular, que possuem elevados níveis de exigência com relação a ruídos espectrais. / This work has as main objective to develop a new source of diode laser compact and robust, beyond a new drive control for use in primary of time and frequency standards type cesium atom fountain and compact standards-based cold atoms. One of the requirements for the use of diode laser in primary of time and frequency standards are their stability in frequency and are very low spectral noise. Furthermore, given the embedded application, the laser must be extremely robust with respect to adverse conditions: mechanical, thermal and electrical. Both opto-mechanical part, as the electronic controls of the new laser were developed in this work. It is noteworthy that such a system, in its conception, is of great interest to many other types of applications such as spectroscopy of gases (LIDAR), references in other frequencies and experiments of atomic and molecular physics, which have high levels of demand with respect to spectral noise.

A pair of high-stability optical frequency references has been developed. The devices are based on room temperature Fabry-Perot cavities with mirrors spaced apart by a hollow single-crystal sapphire element. The sapphire element delivers mechanical sti ness that provides improved immunity to vibrational perturbations compared with the more common spacers made from ultra-low expansion glass. The system is housed in an vacuum chamber designed to provide isolation from environmental perturbations through the use of an active thermal control system, suspension legs and a unique beam alignment system. The dimensional stability of the Fabry-Perot was translated into a highly stable laser frequency by frequency locking a 1064nm Nd:YAG laser to the centre of a mode of the cavity. This frequency lock was implemented by the Pound-Drever-Hall scheme. By careful design, this control system was able to hold the frequency of the laser to within parts in 1016 of the frequency of the fundamental cavity mode. The minimum fractional frequency stability of the laser frequency was measured at 2.1x10[-]14 for integration times of 0.8 s, limited by the residual instability of the Fabry-Perot cavity. The experimental methods used to measure the performance of the system have also been considered in depth. For example, the most common way of characterizing the frequency stability of a frequency standard is the Allan variance. It is demonstrated that, without care, data taken with modern frequency counters can produce erroneous and distorted results when their output is supplied to this algorithm. The method to avoid or account for these errors is also presented. The Fabry-Perot cavity performance is limited on long timescales by residual temperature uctuations, which can be ameliorated in future by enhancing the design of the thermal control system. At short timescales, the system is limited by vibration-induced uctuations together with a white noise source, that is yet to be identi ed, but may relate to fundamental thermodynamic temperature uctuations of the sapphire spacer. This system was used to measure the stability of an optical signal synthesised from a cryogenic microwave sapphire oscillator using an wide-band optical frequency comb. This was the rst demonstration of a multiplication of an ultra-stable signal from the microwave frequency domain into the optical frequency domain, without loss of delity at the level of 2x10[-]14.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 69-75).

Este trabalho tem como objetivo principal desenvolver uma nova fonte de laser de diodo compacta e robusta, além de um novo drive de controle para serem utilizados em padrões primário de tempo e frequência tipo chafariz de átomo de Césio e padrões compacto baseados em átomos frios. Um dos requisitos para utilização de laser de diodo em padrões primários de tempo e frequência é sua estabilidade em frequência e baixíssimo ruído espectral. Além disto, dada à aplicação embarcada, o laser deve ser extremamente robusto com relação às condições adversas: mecânicas, térmicas e elétricas. Tanto a parte optomecânica, quanto os controles eletrônicos do novo laser foram desenvolvidos neste trabalho. Vale salientar que tal sistema, em sua concepção, é de grande interesse para diversos outros tipos de aplicação, como espectroscopia de gases (LIDAR), referências em outras frequências e experimentos de física atômica e molecular, que possuem elevados níveis de exigência com relação a ruídos espectrais. / This work has as main objective to develop a new source of diode laser compact and robust, beyond a new drive control for use in primary of time and frequency standards type cesium atom fountain and compact standards-based cold atoms. One of the requirements for the use of diode laser in primary of time and frequency standards are their stability in frequency and are very low spectral noise. Furthermore, given the embedded application, the laser must be extremely robust with respect to adverse conditions: mechanical, thermal and electrical. Both opto-mechanical part, as the electronic controls of the new laser were developed in this work. It is noteworthy that such a system, in its conception, is of great interest to many other types of applications such as spectroscopy of gases (LIDAR), references in other frequencies and experiments of atomic and molecular physics, which have high levels of demand with respect to spectral noise.

Optical frequency standards with the reference to a narrow electronic transition of a laser-cooled collection of neutral atomic particles are becoming essential tools of research in modern precision physics experiments. In the core of a building block of an optical frequency standard is the optical continuous wave laser that has a good spectral purity of the emitted light. Such a stable optical oscillator is highly desirable in high resolution spectroscopy, if it emits in a good quality beam at a short visible wavelength. This Master thesis explores efficient techniques for building such an optical frequency source intended for use in the cooling and trapping of Calcium atoms scheme. The strong dipole transition at the blue wavelength in the atomic Calcium is needed to reduce the kinetic energy of atoms by nearly six orders of magnitude. A further reduction in the thermal energy of the laser cooled atoms is required to locate with ultra-high precision the 400 Hz narrow clock transition of the stable 40Ca isotope. The experimental methods that achieve this and approach sub-microkelvin temperature of the laser cooled bosonic isotopes of alkaline earths are inspected. The blue laser with a uniform intensity distribution in the beam is useful to maintain the trapped number of cold atoms during these experiments. The spectroscopic properties of the relative transitions in Calcium atom are also reviewed following relevant publications in the area. The constructed blue laser can be used as a primary wavelength source in the lasers network for cooling and trapping of Calcium atoms. These experiments will constitute part of the project to build an optical atom clock referenced to 40Ca narrow linewidth transition. The blue laser is constructed by generating second harmonic in a Potassium Niobate crystal, which is temperature controlled to use a type-I noncritical phase-matching of the optical nonlinear process. The power of the intracavity-generated second harmonic depends on the resonance properties of the optical resonator where this nonlinear crystal is placed. The study is aimed at characterising the designed optical resonator and the experimental parameters that describe it. The formula is derived that relates the resonance power enhancement coefficient with finesse and the power coupling contrast of a passive optical cavity. The obtained relationship is verfied during the experiments. The produced efficiency of the intracavity second harmonic generation is approx. 0.0023 mWblue/(mWred)2. The research work also examines the noise characteristics of the infrared diode laser that is used as a pump source for the intracavity generated second harmonic and determines the spectroscopic precision of the produced blue light. The frequency locking experiment is analysed using the unbalanced scheme of the polarisation stabilisation technique. The designed optical buildup cavity became a part of the unbalanced frequency discriminator in such a scheme. The results demonstrate high gain of frequency noise suppression of the stabilised laser. The unbalanced arrangement of the H}ansch-Couillaud technique has been possible due to a very low amplitude noise of semiconductor lasers.

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