Дисертації з теми "Optical atomic clocks"
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1
Dovale, Alvarez Miguel. "Optical cavities for optical atomic clocks, atom interferometry and gravitational-wave detection." Thesis, University of Birmingham, 2019. http://etheses.bham.ac.uk//id/eprint/8851/.
Повний текст джерелаАнотація:
It is an extremely exciting time for physics. In the last 100 years we moved from the formulation of Einstein's general relativity to the first direct observation of gravitational waves in late 2015 by the Laser Interferometer Gravitational-wave Observatory (LIGO). In that time we learned to use light to cool atoms to nearly absolute zero temperature, and to use atomic transitions in the microwave and optical regimes to devise the most accurate time and frequency references. We observed the wave-like behaviour of cold atoms in diffraction experiments using the periodic structure of light beams. Exploiting this wave-like behaviour, we constructed atom interferometers which allow us to test and measure gravity in a new scale. All of these experiments have one thing in common, from LIGO's giant 4 km arms, to the transportable atomic clocks sent to space, they all make use of a device that has become essential in many areas of science and technology: the Fabry-Perot optical cavity. This thesis delves deeply into the application of optical cavities at the forefront of experimental physics, and it is divided into three parts, each pertaining to a different field where optical cavities are a key technology.
2
Lytle, Christian, and Christian Lytle. "Spectroscopy of Neutral Mercury in a Magneto-Optical Trap Based on a Novel Ytterbium Fiber-Amplified Cooling Laser Source." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621471.
Повний текст джерелаАнотація:
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.
3
Schulte, Marius [Verfasser]. "Entanglement in Ramsey interferometry, optical atomic clocks and trapped ions / Marius Schulte." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/1226286194/34.
Повний текст джерела
4
Lamilla, Rubio Erick Abraham 1985. "Transmitindo padrões de frequência atômicos por redes de fibras ópticas=Transmitting atomic frequency standards in optical fiber networks." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276939.
Повний текст джерелаАнотація:
Orientadores: Flavio Caldas Da Cruz, Luiz Eduardo Evangelista de AraujoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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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
5
Bridge, Elizabeth Michelle. "Towards a strontium optical lattice clock." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:a96e73fe-f17b-4738-be1d-34429b5b4a05.
Повний текст джерелаАнотація:
Due to the recent success, in terms of accuracy and precision, of a number of strontium optical lattice optical frequency standards, and the classification of the 5s2 1S0 to 5s5p 3P0 transition in neutral strontium as a secondary definition of the SI unit of the second, many new strontium lattice clocks are under development. The strontium optical lattice clock (Sr OLC) at the National Physical Laboratory (NPL) is one such project. This thesis describes the design and build of the NPL Sr OLC, discussing the considerations behind the design. Details of the first cooling stage are given, which includes the characterisation of a novel permanent-magnet Zeeman slower by measurements of the longitudinal velocity distributions and loading of the MOT at 461 nm. Development of a narrow linewidth laser system at 689 nm is described, which is used for initial spectroscopy of the second-stage cooling transition. In particular, this work describes progress towards two independent ultra-narrow linewidth clock lasers. The new generation of strontium lattice clock experiments have focused on characterising the systematic frequency shifts and reducing their associated fractional frequency uncertainties, as well as reducing the fractional frequency instability of the measurement. One focus of the Sr OLC at NPL is to help characterise the frequency shift of the clock transition due to black-body radiation (BBR), which is currently the largest contributor to the uncertainty budget of the measured clock frequency. Our approach, discussed here, is to make a direct, differential measurement of the shift with the atoms housed alternately in environments of differing temperatures. Better characterisation and control of the BBR frequency shift of the strontium clock transition is crucial for the future of the Sr OLC as a leading frequency standard.
6
King, Steven Anthony. "Sub-hertz optical frequency metrology using a single ion of 171Yb+." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:428b1f40-3b5d-475e-aebc-c062b987e3f2.
Повний текст джерелаАнотація:
Optical frequency standards offer the possibility of a step improvement of up to two orders of magnitude in the accuracy with which the SI second can be realised. 171Yb+ possesses two dipole-forbidden optical transitions that are promising candidates for a redefinition of the second. In this thesis, absolute frequency measurements of these two transitions are presented. A number of experimental upgrades have been implemented, which have resulted in a large reduction in both the statistical and systematic uncertainties associated with the measurements and have improved both the reliability and simplicity of the experimental setup. In particular, the replacement of two frequency-doubled Ar+-pumped Ti:sapphire lasers with extended cavity diode lasers has eliminated the downtime associated with their maintenance. Additionally, the introduction of polarisation modulation on the cooling light has allowed the residual bias magnetic field required for laser cooling to be reduced by a factor of thirty. The first measurement at the National Physical Laboratory (NPL) of the frequency of the 2S1/2 (F = 0) → 2D3/2 (F′ = 2) electric quadrupole (E2) transition at 436 nm is presented. The transition frequency was measured against a hydrogen maser using a femtosecond optical frequency comb, and was determined with a relative standard uncertainty of 1.3 × 10−14. A commercial diode-based laser system was then implemented in order to drive the 2S1/2 (F = 0) → 2F7/2 (F′ = 3) electric octupole (E3) transition at 467 nm. The laser frequency was actively stabilised to the ultra-narrow atomic absorption with a resolved linewidth of 11 Hz, allowing the acquisition of ninety hours of frequency data measured relative to the NPL’s primary frequency standard CsF2. Combined with a thorough evaluation of the systematic perturbations, the total fractional uncertainty in the absolute frequency of the transition has been reduced by a factor of twenty to 1 × 10−15. Recent complementary results from Physikalisch-Technische Bundesanstalt (PTB) show that the E3 transition in 171Yb+ has the potential to be a highly accurate and reproducible optical frequency standard, and to date these measurements demonstrate the best international agreement between trapped ion optical frequency standards.
7
Petersen, Michael. "Laser-cooling of Neutral Mercury and Laser-spectroscopy of the 1S0-3P0 optical clock transition." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00405200.
Повний текст джерела
8
Maximo, Carlos Eduardo. "Collective scattering of light from disordered atomic clouds." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-28022018-142502/.
Повний текст джерелаАнотація:
In this thesis, we investigate the coherent scattering of light by atoms randomly distributed in space. As described by a model of coupled dipoles, the cooperation in the spontaneous emission process results from purely optical interactions between the atomic internal degrees of freedom. In the optically dilute regime, where the atomic medium can be described by a refractive index, we have shown that light can be deflected with the application of a gradient of magnetic field. In the dense regime, short-range interactions appear to suppress Anderson localization of light even in two dimensions, a result which disassembles the common belief that all waves are localized in two dimensions. We also find that the fringe pattern, resulting from the interference between light scattered by an atomic cloud and that of its specular image, is robust to both disorder averaging and saturation. Finally, we demonstrate two-atom bound states in the two-dimensional motion through the long-range optical coupling. This optical binding effect with an atom pair will be important to investigate the all-optical stabilization of large clouds.Nesta tese, investigamos o espalhamento coerente de luz por átomos distribuídos aleatoriamente no espaço. Conforme descrito por um modelo de dipolos acoplados, a cooperação no processo de emissão espontânea resulta de interações puramente ópticas entre os graus internos de liberdade dos átomos. No regime opticamente diluído, onde o meio atômico pode ser descrito por um índice de refração, mostramos que a luz pode ser desviada com a aplicação de um gradiente de campo magnético. No regime denso, as interações de curto alcance parecem suprimir a localização de Anderson da luz mesmo em duas dimensões, resultado que desmonta a crença comum de que todas as ondas estão localizadas em duas dimensões. Também descobrimos que o padrão de franjas, resultante da interferência entre a luz espalhada por uma nuvem atômica e a de sua imagem especular, é robusto tanto contra a média em disordem quanto contra saturação. Finalmente, demonstramos estados ligados de dois átomos no movimento bidimensional através do acoplamento óptico de longo alcance. Este optical binding effect com um par de átomos será importante para investigar a estabilização totalmente óptica de nuvens extensas.
9
Abdel, Hafiz Moustafa. "Development and metrological characterization of a high-performance Cs cell atomic clock based on coherent population trapping." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD035/document.
Повний текст джерелаАнотація:
Ce travail de thèse, effectué dans le cadre du projet européen MClocks (http://www.inrim.it/mclocks), reporte le développement et la caractérisation métrologique d’une horloge atomique à cellule de césium de haute performance basée sur le phénomène de piégeage cohérent de population (CPT). Cette horloge exploite un schéma de pompage CPT optimisé nommé push-pull optical pumping (PPOP), permettant la détection de résonances CPT à fort contraste sur la transition d’horloge 0-0. Une caractérisation détaillée des différents éléments de l’horloge est reportée. L’horloge fut exploitée en mode continu (CW) et en mode impulsionnel de type Ramsey. Dans les deux modes de fonctionnement, l’horloge démontre une stabilité relative de fréquence de l’ordre de 2 10−13 τ−1/2 jusque 100 s d’intégration, principalement limitée par des effets de puissance laser. Cette horloge atomique, parmi les meilleures horloges à cellule développées à travers le monde, pourrait trouver des applications pour les systèmes de télécommunications, d’instrumentation, de défense ou navigation par satellite.Cette thèse reporte aussi une technique originale de stabilisation de fréquence laser par spectroscopie sub-Dopplerbi-fréquence en cellule. La plateforme constituée par l’horloge a été utilisée pour mener des tests de physique plus amont incluant la caractérisation par spectroscopie CPT d’une cellule de césium avec un revêtement anti-relaxant OTS (octadecyltrichlorosilane) ou la caractérisation de microcellules à vapeur de césium avec gaz tampon développées à FEMTO-ST pour des horloges atomiques miniaturesThis thesis work, performed in the frame of the MClocks European project (http://www.inrim.it/mclocks), reports the development and metrological characterization of a high-performance Cs vapor cell atomic clock based on coherent population trapping (CPT). The clock uses an optimized CPT pumping scheme, named push-pull optical pumping (PPOP), allowing the detection of high-contrast CPT resonances on the 0-0 magnetic-field insensitive clock transition. A detailed characterization of key components of the clock is reported. The clock was operated in the continuous-wave (CW) regime and in a Ramsey-like pulsed regime. In both regimes, the clock demonstrates a short-term fractional frequency stability at the level of 2 10−13 τ−1/2 up to 100 s averaging time, mainly limited by laser power effects. This CPT clock, ranking among the best microwave vapor cell atomic frequency standards, could find applications in telecommunication, instrumentation, defense or satellite-based navigation systems.This thesis reports also a novel laser frequency stabilization technique using dual-frequency sub-Doppler spectroscopy in a vapor cell. The clock ”platform” has also been used to perform using CPT spectroscopy the characterization of a Cs vapor cell coated with octadecyltrichlorosilane (OTS) or original buffer-gas filled Cs vapor micro-fabricated cells developed in FEMTO-ST for CPT-based miniature atomic clocks
10
Bilicki, Sławomir. "Horloges à réseau optique au strontium : comparaisons d'horloges pour des applications en physique fondamentale et échelles de temps." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066247/document.
Повний текст джерелаАнотація:
Cette thèse est consacrée aux progrès récents des horloges à réseau optique au strontium du LNE-SYRTE, Observatoire de Paris. L'incertitude systématique et la stabilité des horloges optiques sont 2 ordres de grandeur meilleures que les horloges atomiques micro-ondes au cesium qui réalisent la seconde SI, bénéficiant maintenent a des applications en physique fondamentale, astronomie et géosciences. Dans un futur proche, une redéfinition de la seconde SI est attendue, quand les horloges optiques se seront révélées aussi fiables et reproductibles que les horloges a micro-ondes. La thèse présente trois étapes décisives dans cette direction. Nous présentons un fonctionnemment operation quasi-continu de nos horloges Sr pendant plusieurs semaines. Des comparaisons de fréquences locales et à distance avec diverses références de fréquence micro-ondes et optiques montrent que les horloges optiques sont reproductibles par des laboratoires independants. Nous avons démontré un premier réseau tout optique entre des horloges optiques à l'échelle continentale. Les horloges au Sr ont été utilisées pour préparer 5 rapports de calibration du Temps Atomique International (TAI) qui ont été validés par le BIPM comme première contribution au TAI par des horloges optiques. Certains de ces résultats ont été utilisés pour borner l'amplitude d'une possible violation de l'invariance de Lorentz analysant les comparaisons d'horloges distantes. Enfin, nous avons effectué une caractérisation complète des déplacements de fréquence associés aux sources laser à semiconducteur utilisées pour le piégeage des atomes dans l'optique d'applications pour des horloges transportables et spatialesThis thesis describes the latest progresses regarding the Sr optical lattice clocks at LNE-SYRTE, Observatoire de Paris. Nowadays, the systematic uncertainty and stability of optical clocks are 2 orders of magnitude better than cesium microwave fountains currently realizing the SI second, with applications in fundamental physics, astronomy and geoscience. In the near future, a re-definition of the SI second is expected, once optical clocks are proven to be as reliable and reproducible as their microwave counterparts. The thesis presents three decisive steps in this direction. First, we demonstrate nearly continuous Sr clocks over several weeks. Second, local and remote frequency comparisons against various microwave and optical frequency standards show that OLCs are reproducible over time, and by independent laboratories. We notably demonstrated the first all-optical agreement between optical clocks at continental scale. Third, the Sr clocks were used to calibrate the Temps Atomique International (TAI). The five calibration reports, which we produced, were validated by the BIPM, as the first contribution to TAI with optical clocks. In addition, some of these results were used to improve bounds on a putative violation of the Lorentz invariance by testing the stability of the frequency ratio between remote clocks. Finally, we conducted a full characterization of the frequency shifts associated with semi-conductor laser sources for the trapping light, including optical measurements and frequency shifts measurements, with applications for transportable and space clocks
11
Favier, Maxime. "Horloge à réseau optique de mercure : spectroscopie haute-résolution et comparaison d'étalons de fréquence ultra-précis." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066598/document.
Повний текст джерелаАнотація:
L’objet de cette thèse est le développement d’un standard de fréquence optique base sur l’atome de mercure 199Hg piégé dans un réseau optique. Je présenterai le dispositif expérimental et les améliorations apportées au cours de la thèse qui ont permis d’effectuer la spectroscopie de la transition doublement interdite 1S0 – 3P0 du mercure dans le domaine ultraviolet avec une résolution de l’ordre du Hz. Une telle résolution nous a permis de mener une étude approfondie des effets physiques affectant la fréquence de la transition d’horloge. Cette étude a permis un gain d’un facteur 60 sur la connaissance de la fréquence de la transition d’horloge, et de pousser l’incertitude au-delà de la réalisation de la seconde si par les étalons de fréquence basés sur le césium. Enfin je présenterai les résultats de plusieurs campagnes de comparaison entre notre étalon au mercure et d’autres horloges de très haute précision fonctionnant dans le domaine optique ainsi que dans le domaine micro-ondeThis thesis presents the development of a high-accuracy optical frequency standard based on neutral mercury 199Hg atoms trapped in an optical lattice.I will present the experimental setup and the improvements that were made during this thesis, which have allowed us to perform spectroscopy on the doubly forbidden 1S0 - 3P0 mercury clock transition with Hz level resolution. With such a resolution, we have been able to conduct an in-depth study of the physical effects affecting the clock transition. This study represents a factor 60 in accuracy on the knowledge of the clock transitions frequency, pushing the accuracy below the current realization of the si second by the best cesium atomic fountains. Finally, i will present the results of several comparison campaigns between the mercury clock and other state-of-the-art frequency standards, both in the optical and in the microwave domain
12
Mandt, Stephan [Verfasser], Achim Akademischer Betreuer] Rosch, Alexander [Akademischer Betreuer] [Altland, and Ralf [Akademischer Betreuer] Schützhold. "Transport and Non-Equilibrium Dynamics in Optical Lattices : From Expanding Atomic Clouds to Negative Absolute Temperatures / Stephan Mandt. Gutachter: Achim Rosch ; Alexander Altland ; Ralf Schützhold." Köln : Universitäts- und Stadtbibliothek Köln, 2012. http://d-nb.info/1038227941/34.
Повний текст джерела
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Mandt, Stephan Verfasser], Achim [Akademischer Betreuer] Rosch, Alexander [Akademischer Betreuer] [Altland, and Ralf [Akademischer Betreuer] Schützhold. "Transport and Non-Equilibrium Dynamics in Optical Lattices : From Expanding Atomic Clouds to Negative Absolute Temperatures / Stephan Mandt. Gutachter: Achim Rosch ; Alexander Altland ; Ralf Schützhold." Köln : Universitäts- und Stadtbibliothek Köln, 2012. http://d-nb.info/1038227941/34.
Повний текст джерела
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Nuñez, Portela Mayerlin. "Desenvolvimento de um laser de Nd:YLF bombeado por diodo laser e duplicado em freqüência para 657 nm." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277713.
Повний текст джерелаАнотація:
Orientador: Flavio Caldas da CruzDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Os relógios atômicos são usados na atualidade em um grande número de aplicações científicas e tecnológicas que vão desde experimentos de relatividade e determinação de constantes fundamentais, até sistema de navegação (GPS) e telecomunicações. A proxima geração de relógios atômicos de alta precisão estará baseada em transições ópticas de átomos frios. Neste trabalho foi desenvolvido um laser de estado sólido de Nd:YLF bombeado por um laser de diodo e duplicado em frequência em 657 nm. Este sistema é proposto como oscilador local em um relógio atômico óptico baseado em átomos de cálcio. Comparado com os lasers de diodo, este apresenta uma potência maior no vermelho, um ruído de frequência e amplitude menores e a possibilidade de transferência remota usando obras ópticas no comprimento de onda fundamental de 1314 nm. Duplicação em frequência intra-cavidade é feita usando um cristal de BiBO, com superfícies anti-refletoras, e com um casamento de fase crítico tipo I à temperatura ambiente. Uma potência de 270 mW na saída do vermelho foi obtida para uma potência de bombeamento de 11.6 W.
Abstract: Atomic clocks are used today in a number of scientific and technological applications, ranging from tests of relativity, or variations of fundamental constants, to the use in navigation and telecommunication. The next generation of such high precision devices will be based on optical transitions of suitable laser cooled and trapped atoms. In this work we describe a frequency-doubled, diode-pumped solid-state Nd:YLF ring laser emitting at 657 nm, proposed as a local oscillator in an optical atomic clock based on laser cooled and trapped calcium atoms. Compared to diode lasers, its main advantages include higher power, less intrinsic frequency noise, and the possibility of remote transfer in optical fibers using the fundamental light at 1314 nm. Frequency doubling is performed inside the cavity using a 10 mm long AR-coated BiBO crystal, under type I, critical phase-matching at room temperature. Red output power of 270 mW was achieved for 11.6 W of pumping power.
Mestrado
Física Atômica e Molecular
Mestre em Física
15
Bourgain, Ronan. "Diffusion de la lumière dans les nuages denses mésoscopiques d'atomes froids." Phd thesis, Palaiseau, Institut d'optique théorique et appliquée, 2014. http://tel.archives-ouvertes.fr/tel-00978177.
Повний текст джерелаАнотація:
Lorsque l'on place des atomes suffisamment proches les uns des autres, l'interaction dipôle-dipôle résonante entre les atomes modifie leurs propriétés. Les atomes se comportent alors de manière collective. Ces effets collectifs se produisent lorsque les distances interparticulaires sont de l'ordre de l/(2Pi), où l est la longueur d'onde de la transition atomique. La densité atomique est alors de l'ordre de 10^14 at/cm^3. Afin de créer des échantillons d'atomes froids présentant des densités aussi élevées, nous avons mis en place plusieurs méthodes de chargement de nos pinces optiques de taille micrométrique. L'une d'elles utilise un processus d'évaporation forcée qui amène les atomes proches de la dégénérescence quantique. En utilisant des nuages denses contenant quelques centaines d'atomes à des densités spatiales élevées, et en étudiant les modifications de la diffusion de la lumière qui en résultent, nous avons pu mettre en évidence des effets collectifs entre les atomes. Nous avons par ailleurs mesuré le retard de Wigner associé à la diffusion élastique de la lumière par un atome unique de rubidium. Nous avons mesuré un retard proche de la valeur théorique, c'est-à-dire deux fois la durée de vie de la transition atomique (52 ns).
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Radnaev, Alexander G. "Towards quantum telecommunication and a Thorium nuclear clock." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/50120.
Повний текст джерелаАнотація:
This thesis presents the investigations of Rubidium atoms in magneto-optical traps and triply charged Thorium ions in electrodynamic traps for future advances in long-distance quantum telecommunication, next generation clocks, and fundamental tests of current physical theories. Experimental realizations of two core building blocks of a quantum repeater are described: a multiplexed quantum memory and a telecom interface for long-lived quantum memories. A color change of single-photon level light fields by several hundred nanometers in an optically thick cold gas is demonstrated, while preserving quantum entanglement with a remotely stored matter excitation. These are essential elements for long-distance quantum telecommunication, fundamental tests of quantum mechanics, and applications in secure communication and computation. The first trapping and laser cooling of Thorium-229 ions are described. Thorium-229 nuclear electric quadrupole moment is revealed by hyperfine spectroscopy of triply charged Thorium-229 ions. A system to search for the isomer nuclear transition in Thorium-229 is developed and tested with the excitation of a forbidden electronic transition at 717 nm. Direct excitation of the nuclear transition with laser light would allow for an extremely accurate clock and a sensitive test bed for variations of fundamental physical constants, including the fine structure constant.
17
Cambier, Valentin. "Horloge à réseau optique à atomes de mercure exploitant un 2D-MOT : durée de vie de l'état 3P0 et mesures de fréquence." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS512.
Повний текст джерелаАнотація:
Les horloges optiques ont révolutionné la métrologie du temps et des fréquences depuis le début des années 2000. Dans ma thèse, j’ai travaillé avec une horloge à réseau optique basée sur l’atome de mercure. Le mercure est un candidat prometteur pour les horloges à réseau du fait de sa faible sensibilité au rayonnement du corps noir. Durant ma thèse, j’ai exploité un piège magnéto optique 2D pour pré-refroidir les atomes de mercure avant leur interrogation. Cela permet non seulement de piéger un plus grand nombre d’atomes mais aussi d’améliorer le cycle d’horloge en diminuant le temps de cycle total. Ces améliorations ont permis de mesurer la durée de vie de l’état 3P0 et de participer à des campagnes de mesure à l’échelle européenne entre différentes horloges située à plusieurs centaines de kilomètres l’une de l’autre. Nous avons ainsi pu mesurer pour la première fois le ratio de fréquence entre le mercure et l’ion ytterbium +Optical clocks have changed time and frequency metrology since the beginning of the 2000’s. In my thesis, I worked on a mercury optical lattice clock. Mercury is a promising candidate for optical clocks thanks to its weak sensitivity to blackbody radiation shift. During my PhD, I took benefit of a magneto optical trap in two dimensions (2D-MOT) to pre-cool the mercury atoms before the interrogation phase. It allows us not only to trap much more atoms but also to improve the clock cycle by decreasing the total cycle time. These improvements made possible the lifetime measurement of the 3P0 state and to participate to measurement campaigns at the European scale between different clocks located a few hundreds of kilometres apart. As a consequence, it was possible to measure for the first time the frequency ratio between mercury and Yb+ ion
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Gredat, Grégory. "Propriétés de bruit et dynamique de lasers à semiconducteurs en régime d'émission bifréquence pour l'optique micro-ondes et la métrologie." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS109.
Повний текст джерелаАнотація:
L'émission cohérente de deux fréquences optiques présentant un battement radio-fréquence accordable trouve son application dans les liaisons opto-hyperfréquences, utiles aux radars ou radio-télescopes, mais également dans le domaine de la métrologie avec le déport optique de références temps-fréquence ultra-stables. Grâce à un cristal biréfringent à l'intérieur de leur cavité, les lasers à semiconducteurs de type VECSEL (vertical-external-cavity surface-emitting lasers) permettent de générer deux faisceaux corrélés de bonne pureté spectrale, avec une différence de fréquence accordable et polarisés linéairement dans des directions orthogonales. De telles sources lasers ont été développées à la longueur d'onde de la transition D₂ du césium dans le but d'élaborer une horloge atomique exploitant une résonance par CPT (coherent population trapping). L'objectif est de proposer un compromis inédit entre performance et compacité. En plus de caractériser les bruits (intensité et phase) de ces sources lasers, nous exploitons la modélisation de leur dynamique grâce à des équations d'évolution couplées pour minimiser dans un premier temps le transfert de bruit provenant de la pompe et optimiser dans un second temps leur asservissement. Une nouvelle architecture de la pompe optique produisant deux faisceaux corrélés est mise en place pour cette minimisation. La contribution du niveau de bruit mesuré à l'instabilité à court terme de l'horloge CPT est ensuite prédite. Aux basses fréquences, le spectre de bruit de phase du battement généré par le VECSEL bifréquence est dominé par des effets thermo-optiques, principalement causés par le bruit de la pompe. Nous établissons un modèle tenant compte des détails microscopiques du milieu à gain, de l'anisotropie de la diffusion de chaleur, des effets de lentille thermique ou encore des fluctuations thermodynamiques. Nous analysons la matrice de covariance spectrale des bruits d'intensité. Les modes propres des fluctuations sur les polarisations croisées sont alors comparés aux modes symétriques et anti-symétriques. Enfin, une méthode est élaborée pour obtenir une caractérisation et un tri des processus non-stationnaires de bruit particulièrement présents aux basses fréquencesCoherent emission of two optical tones with a radiofrequency (RF) tunable beatnote can spur many microwave photonics applications. Indeed, it can be useful for radars, remote sensing, or in the metrological context of ultra-stable RF frequency standards. A birefringent crystal can be inserted inside the external cavity of a VECSEL (vertical-external-cavity surface-emitting lasers) to produce a tunable very low-noise RF beatnote out of two orthogonal linear polarizations. Such dual-frequency semiconductor lasers operating along the D₂ line of cesium have been developed for CPT (coherent population trapping) atomic clocks. The development of these clocks corresponds to a need to find a trade-off between size and performance. First, intensity and RF beatnote phase noise investigations in these dual-frequency VECSELs are reported. A model based on coupled rate equations allows us to find minimization strategies for the noise transfer from the pump to the laser thanks to a new pumping architecture, which produces two correlated pump spots to feed the laser modes. The laser dynamics is then optimized for efficient noise active suppression. We predict a contribution to the short term relative frequency stability of the CPT clock compatible with an Allan deviation of 5x10⁻¹³ at 1s. Pump induced thermo-optic effects are dominating the low-frequency part of the dual-frequency VECSEL beatnote phase noise spectrum and require to be better understood. A new thermal model is thus established. This model takes into account the details of the gain medium, heat diffusion spatial anisotropy, thermal lens effects and also thermodynamic fluctuations. Besides, an analysis of the spectral intensity noise covariance matrix is initiated. We evidence that the eigen modes of the cross-polarized intensity fluctuations are close to in-phase and anti-phase noise mechanisms. Eventually, we elaborate a novel characterization and ranking method for non-stationary noises, which are often related to low-frequency spurious peaks
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Piotrowski, Marcin. "Zastosowanie metrologiczne zimnych atomów pułapkowanych optycznie." Praca doktorska, 2015. https://ruj.uj.edu.pl/xmlui/handle/item/48897.
Повний текст джерелаАнотація:
Rozprawa omawia wybrane zastosowania metrologiczne zimnych atomów pułapkowanych optycznie na przykładzie dwóch eksperymentów: pułapki dipolowej dla zimnych atomów rubidu oraz sieci optycznej dla atomów strontu, będącej częścią większego przedsięwzięcia: pierwszego polskiego atomowego zegara optycznego. Optyczna pułapka dipolowa dla atomów rubidu powstała w laboratorium Zimnych Atomów Zakładu Fotoniki Uniwersytetu Jagiellońskiego. Celem budowy nowego stanowiska eksperymentalnego jest możliwości badania nieliniowych efektów magnetooptycznych, jak na przykład efekt Fardaya do celów precyzyjnej magnetometrii. W pierwszym etapie atomy rubidu są chłodzone w dwuwymiarowej pułapce magneto-optycznej (2D-MOT), formując strumień wstępnie schłodzonych atomów dla trójwymiarowej pułapki magnetooptycznej (3D-MOT). Proces przeładowania i formowania wiązki i jest szczegółowo opisany i scharakteryzowany.Następnie zimne atomy są do pułapki optycznej dipolowej (ODT), która przestrzennie przekrywa się z 3D-MOT. Rozprawa opisuje wyniki badania efektu Faradaya w optycznej pułapce dipolowej. Sieć optyczna dla atomów strontu jest częścią budowy Polskiego Optycznego Zegara Atomowego (POZA) w Krajowym Laboratorium Fizyki Atomowej, Molekularnej i Optycznej. Szczegółowo opisana jest aparatura tworząca strontowy standard częstotliwości dla zegara atomowego. Omówione są wyniki badania spektroskopii ultra-wąskiego przejścia zegarowego w próbkach atomów Strontu oraz stabilności stworzonego na jego bazie zegara optycznego.Two experiments with laser-cooled atoms held in an optical dipole traps are described in the dissertation. First is dedicated to non-linear magneto-optical effects in rubidium atoms, while second is devoted to optical lattice trap for strontium atoms. Selected metrological applications of optically trapped cold atoms in both experiments are discussed and presented. A dipole trap setup has been built at the Department of Photonics in Jagiellonian University. It is aimed at investigations of nonlinear magneto-optical effects like precise magnetometry by Faraday effect. A compact two-dimensional magneto optical (2D-MOT) trap with permanent magnets serves as a source of cold rubidium atoms for further cooling in three-dimensional magneto-optical trap (3D-MOT). The 2D-MOT is described and characterised. The results of the loading an optical dipole trap (ODT) from a the 3D-MOT are then presented. It is followed by the results of a Faraday rotation of a resonant laser beam with atoms confined in the final stage of confinement in ODT. The strontium lattice experiment is a part of a larger project: the construction of the first polish optical atomic clock (project Polish Optical Atomic Clock) at the National Laboratory for Atomic, Molecular and Optical Physics. An introduction to time and frequency metrology with optical clocks is given. We describe strontium atoms confined in the optical lattice as a frequency reference for the optical clock in detail. The results of precision spectroscopy of ultra- narrow clock transition in bosonic Sr-88 and the measurements of the clock stability based on atomic reference are presented and discussed.