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Jarvis, Kyle. "The blue-detuned magneto-optical trap." Thesis, Imperial College London, 2018. http://hdl.handle.net/10044/1/63833.
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It has been more than 30 years since the first demonstration of a magneto-optical trap (MOT) using sodium atoms. Since then the MOT has revolutionised the field of atomic physics by facilitating the emergence of a broad range of productive avenues of research using atoms prepared at low temperatures and high densities. This thesis describes the development of a novel kind of magneto-optical trap: the blue-detuned MOT. Unlike in all previous MOTs the light is blue detuned from atomic resonances and drives "type-II" transitions that have dark ground-state sub-levels. A discussion of the position-dependent and velocity-dependent forces experienced by an atom or molecule in a MOT is first used to consolidate recent theoretical work and, in particular, to introduce the concept of a blue-detuned MOT. The design and construction of an experiment that has been built to demonstrate a blue-detuned MOT using ⁸⁷Rb is described. A thorough characterisation of this novel MOT has been performed. At high magnetic field gradients, radiation-pressure-limited densities exceeding 10¹¹ cm⁻³ have been reached whilst temperatures are cooled below 30μK by the efficient and robust sub-Doppler cooling mechanisms. The maximum phase-space density measured is 6 x 10⁻⁶, which is higher than in most normal atomic MOTs, comparable to the best dark SPOTs, and a million times higher than that reported for red-detuned type-II MOTs. This makes the blue-detuned MOT particularly attractive for molecules where laser cooling and trapping always uses type-II transitions. For the first time, a study of trap loss due to ultra-cold collisions between atoms occurring in the presence of near-resonant blue-detuned light is undertaken. Finally, the experiment is used to demonstrate many new and unreported configurations of MOT for ⁸⁷Rb, showing that a comprehensive understanding of complicated MOTs is now possible, and presenting a clear direction for further research.
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Bounds, Alistair David. "A Rydberg-dressed magneto optical trap." Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12541/.
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We Rydberg dress a magneto-optical trap of strontium atoms, mixing Rydberg character into atoms as they are cooled and confined. A recently developed tunable high-power narrow-linewidth 319 nm laser is used to excite and characterise triplet Rydberg states in strontium. Off-resonantly dressing a cloud of atoms in a narrow-line MOT operating on the 5s2 1S0 - 5s5p 3P1 transition, we observe a one-body AC Stark shift on the cloud, which we characterise to identify a regime in which only Rydberg dressed atoms are trapped in the MOT. In this cloud the Rydberg dressed atoms are both trapped and cooled. Increasing atomic density in the dressed MOT, plasma formation is observed at densities lower than the density necessary for observation of Rydberg dressed atoms. This plasma is caused by a build-up of charges due to spontaneous ionisation of Rydberg atoms, which then DC Stark shift the Rydberg state onto resonance with the coupling laser. The high charge density of the plasma then results in strong Rydberg excitation that causes rapid depletion of atoms. Regimes using optimum Rydberg states and charge-extracting electric fields are identified that may prevent plasma formation, and allow the interacting regime to be reached. Such a regime, with cooling, confinement, and tunable interactions, may form the basis of a quantum simulator for dissipative many-body systems.
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Nguyen, Hai Truong. "Magneto optical trap recoil ion momentum spectroscopy /." Search for this dissertation online, 2003. http://wwwlib.umi.com/cr/ksu/main.
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Hambach, Moritz. "Development of a magneto-optical trap for CaF molecules." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/54851.
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Laser cooling and trapping in a magneto-optical trap (MOT) have been essential to the success of cold atom physics in the last decades. Recently, the application of the same techniques to molecules has begun. The complexity of even a simple diatomic molecule makes laser cooling difficult, but promises new applications in many areas of research. In this thesis I describe the development of the first three-dimensional MOT of calcium fluoride (CaF) molecules. First, a cryogenic buffer gas source was set up, producing a pulsed beam of 9.3*10^10 molecules per steradian per pulse with forward velocities around 170 m/s. A similar source for very large molecules was set up during a 5 month internship at the University of Vienna. Next, the molecular pulse was slowed down to the capture velocity of a MOT using chirped laser slowing, resulting in about 7*10^5 CaF molecules passing through the typical MOT volume of 1 cm^3 at velocities of 15+-5 m/s. A new deceleration method, called Zeeman-Sisyphus deceleration, was also investigated. In this method molecules move through a spatially varying magnetic field and are optically pumped between low- and high-field seeking states in such as a way that they are always losing kinetic energy. The method promises to deliver more slow molecules because the molecules are guided transversely as they are decelerated. A small prototype was built and the optical pumping step was tested successfully. Finally, 7.6*10^3 CaF molecules were trapped in a MOT and cooled to a temperature of 8.5 mK. The radial trap frequency is 2 pi*130 Hz and the damping constant is beta=9.5*10^2 s^-1. The lifetime is about 100 ms and depends strongly on the scattering rate. This MOT is an an ideal starting point for a wide range of new experiments with ultracold molecules.
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Elnour, Huzifa Mohammed Ahamed Mohammed. "Development of a magneto optical trap for Rubidium 87." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85586.
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Thesis (MSc)-- Stellenbosch University, 2013.ENGLISH ABSTRACT: A Magneto Optical Trap (MOT) is a configuration formed by three orthogonal pairs of counterpropagating circularly polarized laser beams and a magnetic field gradient. A MOT is used to cool, capture and trap large numbers of atoms in vacuum at very low temperature in K range. In this thesis the development of an experimental setup for realising a MOT of 87Rb atoms is presented. The atomic structure of Rb and the theoretical background of laser cooling and magneto optical trapping was reviewed. The influence of rubidium background pressure in the vacuum system, the laser beam size and the power and frequency on the number of the trapped atoms were studied in literature. The trapping and repumping lasers were characterised experimentally. Six circularly polarised trapping beams with equal power were formed and properly aligned to intersect at the center of the trapping cell. Two optical setups were designed and exploited to investigate and optimise the trapping beam polarisation. The repumping laser beam was successfully aligned and colinearly combined into all the trapping beams. Three different experimental setups for saturated absorption spectroscopy were developed. Saturated absorption spectra showing the hyperfine structure of both 85Rb and 87Rb isotopes were measured and are discussed. Using two saturated absorption spectroscopy setups, the frequencies of both lasers were successfully locked to the trapping and repumping transitions of 87Rb respectively. A rectangular trapping cell was designed and attached to the vacuum system. A pressure of about 10¯7 mbar was achieved. The magnetic field coils were characterised and affixed on both sides of the cell in an anti-Helmholtz configuration. Setups for imaging and quantification of the 87Rb atoms in the MOT were designed. Finally, the procedures for demonstrating a MOT are presented. In conclusion, the current status of the project is reported, with recommendations for the future work.
AFRIKAANSE OPSOMMING: ’n Magneto optiese val (Magneto Optical Trap, MOT) is ’n konfigurasie wat gevorm word deur drie ortogonale laserbundelpare, wat elk uit twee sirkelvormig gepolariseerde bundels met teenoorgestelde voortplantingsrigtings bestaan, en ’n magneetveld gradient. ’n MOT word gebruik om ’n groot aantal atome af te koel, te vang en vas te hou in vakuum by ’n baie lae temperatuur in die K bereik. In hierdie tesis word die ontwikkeling van ’n eksperimentele optelling vir die realisering van ’n MOT van 87Rb atome voorgelê. Die atoomstruktuur van Rb en die teoretiese agtergrond van laser afkoeling en ’n magneto optiese val is hersien. Die invloed van die rubidium agtergronddruk in die vakuumstelsel, die grootte van die laserbundels en die laser drywing en frekwensie op die aantal gevangde atome is bestudeer uit die literatuur. Die MOT-laser en die optiese pomplaser is eksperimenteel gekarakteriseer. Ses sirkelvormig gepolariseerde MOT-laserbundels met gelyke drywings is gevorm en behoorlik belyn om in die middel van die MOT-sel te kruis. Twee optiese opstellings is ontwerp en gebruik om die polarisasie van die MOT-laserbundels te ondersoek en te optimeer. Die optiese pomplaserbundel is suksesvol belyn en ko-liniêr ekombineer met al die MOT-laserbundels. Drie verskillende eksperimentele opstellings vir versadigde absorpsie spektroskopie is ontwikkel. Versadigde absorpsie spektra wat die hiperfyn struktuur van beide die 85Rb en 87Rb isotope toon is gemeet en bespreek. Deur twee versadigde absorpsie spektroskopie opstellings te gebruik is die frekwensies van beide lasers suksesvol gestabiliseer op die MOT- en optiese pomp-oorgange van 87Rb onderskeidelik. ’n Reghoekige MOT-sel is ontwerp en aangesluit by die vakuumstelsel. ’n Druk van ongeveer 10¯7 mbar is bereik. Die magneetveld spoele is gekarakteriseer en weerskante van die sel gemonteer in ’n anti-Helmholtz konfigurasie. Ten einde word die prosedures vir die demonstrasie van ’n MOT voorgelê. In die gevolgtrekking word daar verslag gedoen oor die status van die projek, met aanbevelings vir toekomstige werk.
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Rushton, Joseph. "A novel magneto-optical trap for integrated atom chips." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/382951/.
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This thesis describes the design and construction of a new magneto optical trap that is suitable for use in integrated atom chips and other vacuum systems in which optical access is limited to a single window. The trap design relies on the switching of optical and magnetic fields and can operate at frequencies at least within the region of 1 kHz to 60 kHz. The design does not need patterned surfaces in order to generate the necessary beam geometry, requiring only the use of a single, standard mirror. Early temperature measurements have indicated that the trap may be capable of sub-Doppler cooling, and that it is able to capture on the order of 1:7 � 106 atoms in a capture volume of 0:18 cm3.
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Muckley, Eric S. "Constructing a magneto-optical trap for cold atom trapping /." Click here to view, 2009. http://digitalcommons.calpoly.edu/physsp/2.
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Thesis (B.S.)--California Polytechnic State University, 2009.Project advisor: Katharina Gillen. Title from PDF title page; viewed on Jan. 14, 2010. Includes bibliographical references. Also available on microfiche.
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Hopkins, Stephen Antony. "Laser cooling of rubidium atoms in a magneto-optical trap." n.p, 1995. http://oro.open.ac.uk/19431/.
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Grünert, Jan. "Ultracold metastable calcium atoms in a bichromatic magneto-optical trap." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965196445.
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Hopkins, Stephen. "Laser cooling of rubidium atoms in a magneto-optical trap." Thesis, Open University, 1996. http://oro.open.ac.uk/19431/.
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This thesis describes theoretical and experimental work concerning radiation forces on atoms, with particular reference to rubidium atoms confined in a magneto-optical trap. After a short history of the field of laser cooling, a review of the semiclassical theory of mechanical interactions between two-level atoms and electromagnetic radiation is given. Different formulations of the semiclassical theory are discussed, including a new formulation in terms of momentum transfer amongst the plane wave modes of the electromagnetic field. Two important applications of light forces on atoms, namely 'optical molasses' and the 'magneto-optical trap', are then described with emphasis on experimental parameters. Three sub-Doppler cooling mechanisms, 'sisyphus cooling', 'motion-induced orientation cooling' and the 'magnetically-assisted sisyphus effect', are described and their role in optical molasses and the magneto-optical trap is discussed. A new study of the polarisation gradients which occur in 3-D monochromatic light fields is presented and quantifies their relative presence in different light field configurations. Polarisation gradient parameters are developed and shown to be directly related to the relativistic spin tensor of the light field. Implications of this polarisation gradient study for laser cooling work are discussed. The design, construction from scratch, operation and testing of a magneto-optical trap for rubidium are described, including novel designs for two vacuum cells. Preliminary experiments to characterise the trap are described and results are presented; they primarily concern the number and distribution of atoms in the trap. Finally. the theory of time domain spectroscopy is reviewed. The construction and testing of a pulsed dye laser for study of coherent transients in samples of laser-cooled atoms and a proposed experiment to measure the temperature of cold atoms using coherent transients are described. Factors expected to influence the shape of coherent transients in cold atoms are discussed.
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Patel, Sunil. "A chirped, pulsed laser system and magneto-optical trap for rubidium." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/66245/.
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This thesis covers the construction and characterisation of a magneto-optical trap (MOT) for 85Rb from the very beginning. It details both the optical and mechanical aspects from laser diode assembly, tuning and stabilisation to the preparation and assembly of the vacuum system. The MOT construction forms the first goal of the project, the second was to develop a laser system capable of producing custom programmable, amplitude modulated and frequency chirped pulses (on the tens of microseconds timescale) from a continuous wave source. This involved developing software and computer control for several arbitrary signal generators linked to drivers for acousto-optic and electro-optic modulators. This chirped, pulsed laser system will be used to perform state manipulations on the 85Rb MOT cloud using two-photon Raman transitions in an adiabatic rapid passage regime. The chirped pulse system was initially tested with a rubidium vapour cell in an attempt to perform atomic interferometry that would produce spatial interference fringes along the length of the cell. However, due to the beam power requirements, the beam diameter together with the large Doppler shift at room temperature meant these fringes were not seen and so the vapour cell was replaced with the cold atom cloud in the MOT. Two-photon experiments were attempted with the MOT cloud using the chirped pulse system, however despite greatly improved laser power and detection eficiency, the signal indicating ground state population transfer via a two-photon interaction was not seen. The results indicate that the hyperfine-ground state splitting frequency has been shifted due to the proximity of the ion pump magnet to the vacuum system. Presently, efforts are being directed towards searching for the correct frequency.
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Patel, Sailesh. "Magneto-optical studies of 2D, 1D and 0D electron systems." Thesis, University of Exeter, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337804.
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Yu, QinQin. "Characterization of a two-color magneto-optical trap for a spin-squeezed optical lattice clock." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100323.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 57-58).
We experimentally realize a magneto-optical trap (MOT) for ytterbium that simultaneously scatters light from two atomic transitions, in order to reduce the minimum magnetic field gradient required for trapping atoms. From the experimental data, we propose a model of the MOT where one transition is responsible for trapping the atoms the other transition is responsible for cooling the atoms. In order to test this model and to better understand the dynamics of this two-color MOT, we perform numerical simulations of the contributions of each transition to the steady-state number of trapped atoms. We then compare the results of the simulations with the experimental results and conclude that the model of the separated trapping and cooling functions is a good model for the two-color MOT. Finally, we examine other elements for which the two-color MOT is possible and derive a condition for the linewidths of the two transitions such that the atoms are trapped.
by QinQin Yu.
S.B.
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Gattobigio, Giovanni Luca. "Manipulation of a large magneto-optical trap : application to four-wave mixing." Nice, 2008. http://www.theses.fr/2008NICE4022.
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Martin, Paul. "Development of a Strontium Magneto-Optical Trap for Probing Casimir–Polder Potentials." Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22797.
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In recent years, cold atoms have been the centerpiece of many remarkably sensitive measurements, and much effort has been made to devise miniaturized quantum sensors and quantum information processing devices. At small distances, however, mechanical effects of the quantum vacuum begin to significantly impact the behavior of the cold-atom systems. A better understanding of how surface composition and geometry affect Casimir and Casimir--Polder potentials would benefit future engineering of small-scale devices. Unfortunately, theoretical solutions are limited and the number of experimental techniques that can accurately detect such short-range forces is relatively small.
We believe the exemplary properties of atomic strontium---which have enabled unprecedented frequency metrology in optical lattice clocks---make it an ideal candidate for probing slight spectroscopic perturbations caused by vacuum fluctuations.
To that end, we have constructed a magneto-optical trap for strontium to enable future study of atom--surface potentials, and the apparatus and proposed detection scheme are discussed herein. Of special note is a passively stable external-cavity diode laser we developed that is both affordable and competitive with high-end commercial options.
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Myers, Jessica Ann, and Jessica Ann Myers. "Hybrid Optical-Magnetic Traps for Studies of 2D Quantum Turbulence in Bose-Einstein Condensates." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625625.
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Turbulence appears in most natural and man-made flows. However, the analysis of turbulence is particularly difficult. Links between microscopic fluid dynamics and statistical signatures of turbulence appear unobtainable from the postulates of fluid dynamics making turbulence one of the most important unsolved theoretical problems in physics. Two-dimensional quantum turbulence (2DQT), an emerging field of study, involves turbulence in two-dimensional (2D) flows in superfluids, such as Bose-Einstein condensates (BECs). In 2D superfluids, a turbulent state can be characterized by a disordered distribution of numerous vortex cores. The question of how to effectively and efficiently generate turbulent states in superfluids is a fundamental question in the field of quantum turbulence. Therefore, experimental studies of vortex nucleation and the onset of turbulence in a superfluid are important for achieving a deeper understanding of the overall problem of turbulence.
My PhD dissertation involves the study of vortex nucleation and the onset of turbulence in quasi-2D BECs. First, I discuss experimental apparatus advancements that now enable BECs to be created in a hybrid optical-magnetic trap, an atom trapping configuration conducive to 2DQT experiments. Next, I discuss the design and construction of a quantum vortex microscope and initial vortex detection tests. Finally, I present the first experiments aimed at studying 2DQT carried out in the updated apparatus. Thermal counterflow in superfluid helium, in which the normal and superfluid components flow in opposite directions, is known to create turbulence in the superfluid. However, this phenomenon has not been simulated or studied in dilute-gas BECs as a possible vortex nucleation method. In this dissertation, I present preliminary data from the first experiments aimed at understanding thermal counterflow turbulence in dilute-gas BECs.
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Shah, Mudessar H. "Model-independent measurement of the excited fraction in a magneto-optical trap(MOT)." Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/235.
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Van, Dongen Janelle. "Simultaneous cooling and trapping of 6Li and 85/87Rb." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/351.
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This thesis provides a summary of the laser system constructed in the Quantum Degenerate Gases Laboratory for laser cooling and trapping of 85/87Rband 6Li as well as of experiments that have been pursued in our lab to date. The first chapter provides an overview of the experimental focus of the QDG lab. The second and third chapters provide the fundamental theory behind laser cooling and trapping. The fourth chapter provides details of the laser system. The fifth chapter describes an experiment performed on the subject of dual-injection, performed in collaboration with Dr. James Booth of the British Columbia Institute of Technology (BCIT) involving the dual-injection of a single slave amplifier. The last chapter describes the progress made on the experimental setup needed for the study of Feshbach resonances between 85/87Rb and 6Li and the photoassociative formation of molecules.
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Cook, Eryn. "Laser Cooling and Trapping of Neutral Strontium for Spectroscopic Measurements of Casimir-Polder Potentials." Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23192.
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Casimir and Casimir-Polder effects are forces between electrically neutral bodies and particles in vacuum, arising entirely from quantum fluctuations. The modification to the vacuum electromagnetic-field modes imposed by the presence of any particle or surface can result in these mechanical forces, which are often the dominant interaction at small separations. These effects play an increasingly critical role in the operation of micro- and nano-mechanical systems as well as miniaturized atomic traps for precision sensors and quantum-information devices. Despite their fundamental importance, calculations present theoretical and numeric challenges, and precise atom-surface potential measurements are lacking in many geometric and distance regimes.
The spectroscopic measurement of Casimir-Polder-induced energy level shifts in optical-lattice trapped atoms offers a new experimental method to probe atom-surface interactions. Strontium, the current front-runner among optical frequency metrology systems, has demonstrated characteristics ideal for such precision measurements. An alkaline earth atom possessing ultra-narrow intercombination transitions, strontium can be loaded into an optical lattice at the “magic” wavelength where the probe transition is unperturbed by the trap light. Translation of the lattice will permit controlled transport of tightly-confined atomic samples to well-calibrated atom- surface separations, while optical transition shifts serve as a direct probe of the Casimir-Polder potential.
We have constructed a strontium magneto-optical trap (MOT) for future Casimir-Polder experiments. This thesis will describe the strontium apparatus, initial trap performance, and some details of the proposed measurement procedure.
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Ladouceur, Keith. "Experimental advances toward a compact dual-species laser cooling apparatus." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2508.
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This thesis describes the advances made towards a dual-species magneto-optical trap (MOT) of Li and Rb for use in photoassociation spectroscopy, Feshbach resonance studies, and, as long-term aspirations, the formation of ultracold heteronuclear polar molecules. The initial discussion will focus on a brief theoretical overview of laser cooling and trapping and the production of ultracold molecules from a cold atom source. Subsequently, details of the experimental system, including those pertaining to the required laser light, the vacuum chamber, and the computer control system will be presented. Finally, preliminary optimization and characterization measurements showing the performance of a single species Li MOT are introduced. These measurements demonstrated the loading of over 8 x 107 Li atoms directly into a MOT without the need for a Zeeman slower.
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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.
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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.
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Salas, Andres David Rodriguez. "Geração de uma armadilha magneto-óptica de estrôncio 88." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-05112012-155605/.
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Neste trabalho é apresentada a construção da montagem de um sistema experimental para resfriar átomos de estrôncio. A construção do sistema está focada no estudo do espalhamento coletivo em nuvens atômicas frias e ultrafrias por meio da teoria de Mie. O estrôncio é um elemento que conta com dois estágios de resfriamento, o primeiro utilizando a transição forte entre estados singletos ¹S₀-¹P ₁ de Γ = (2 π)32 MHz, e o segundo com uma transição fraca entre estados singleto e tripleto ¹S₀-³P₁ de Γ = (2 π)7,5 MHz. O objetivo deste trabalho é a construção do sistema para resfriar átomos de estrôncio utilizando a primeira transição. A construção do sistema se apresenta em várias partes, primeiro a construção do um forno como fonte de vapor de estrôncio, onde o estrôncio metálico é aquecido até uma temperatura T = 600°C. O forno conta com um sistema de microtubos encarregados de colimar o feixe atômico, estes microtubos tem um diâmetro interno D ≈ 180µm e um comprimento de 8mm. Depois da implementação do forno e do sistema de microtubos foi medido o perfil de velocidades transversais e a divergência do feixe atômico que sai do forno. A largura tem um valor wr = (2π)108 MHze a divergência do feixe de α ≈4,12. A segunda parte do sistema conta com a construção do desacelerador Zeeman, responsável por desacelerar os átomos do feixe atômico utilizando um feixe laser contrapropagante de λ=461 nm, circularmente polarizado e com uma dessintonização utilizada, após a caracterização do sistema, de Δ=(-2π)580MHz. Os átomos sentiram os efeitos da força de pressão radiativa dentro de um tubo de comprimento de 0,28m. Para compensar o efeito Doppler causado pelo movimento dos átomos foi utilizado um arranjo de bobinas em configuração spin flip para gerar o campo. A terceira e principal parte do sistema foi a construção da armadilha magnetoóptica (AMO). Onde os átomos que saem do desacelerador Zeeman são confinados e resfriados pela combinação de seis feixes contrapropagantes, dos quais três são retrorefletidos utilizando a transição Γ=(2π)32MHz. A dessintonia dos feixes após da caracterização do sistema foi de Δ=(-2π)39MHz. Depois da construção do sistema foi feita a primeira caracterição da armadilha magneto-óptica de átomos de estrôncio 88 em nosso grupo, onde obtivemos a temperatura dos átomos na armadilha para o eixo vertical da expansão foi de Tv=4.7mK e para o eixo horizontal de TH=4mK. Também foi medido o tempo de carga dos átomos na armadilha tcarga=0.15s como bombeamento óptico de estado ³P₂-³D₂. O tempo de vida foi de 0.3s e 0.03s com e sem bombeamento óptico, respectivamente.This work presents the construction of the assembly of an experimental system for cooling strontium atoms. The construction of the system is focused on the collective scattering in atomic cold cloud and ultra cold using the Mie theory. The strontium is an element that permits two stage of cooling, the first using the strong transition between singlet states ¹S₀-¹P₁ of Γ=(2π) 32 MHz, and a second stages is the weak transition between singlet and triplet states ¹S₀-³P₁ de Γ=(2π) 7.5MHz. The objective of this work is building the system for cooling strontium atoms using the first transition. The construction of the system is presented in several parts. First is described the construction of oven as vapor source strontium, where the strontium metal is heated to Temperature Range T = 600°C. The oven has a microtubule system responsible for collimating the atomic beam, these microtubules has an internal diameter of D ≈ 180µm and a length of 8mm. After implementation of the oven system and the microtubes were measured transverse velocity profile and the divergence of the atomic beam that leaves the oven, the width value was f wr=(2π)108MHzand beam divergence value was α ≈ 4,12. The second part of the system relies on the construction of the Zeeman slower responsible for decelerating the atoms of the atomic beam using a laser beam antipropagating of λ = 461 nm nm with a circularly polarized , the detuning used after of the characterization of the system was Δ = (2π)580 MHz. Atoms felt the effects of pressure force radiative within a tube length of 0.28m to compensate the Doppler shift due to motion a of atoms used an arrangement of coils in configuration \"spin flip\" to generate the magnetic field to compensate this effect. The third and main part of the system was the construction of magneto-optical trap (MOT), the atoms coming out of the Zeeman decelerator are confined and cooled by a combination of six counterpropagating beams, three of which are retro reflected using the transition Γ = (2π)32MHz, the detuning of the beam after the characterization of the system was Δ = (-2π) 39 MHz and the opposite polarization for each pair of beam in the same direction. After the construction of the system was made the first magneto-optical trap of strontium atoms 88, the temperature of the trap was atoms to the vertical he expansion was Tv = 4.7mK and the horizontal axis TH = 4 mK 4, also was measured loading time of the atoms in the trap tcharge = 0.15s as optical pumping state ³P₂- ³D₂. The lifetime with and without optical pumping was tlife = 0.3s and tlife = 0.03s respectively.
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Gattobigio, Giovanni Luca. "Manipulation of a Large Magneto-Optical Trap:application to Four-Wave Mixing." Phd thesis, Université de Nice Sophia-Antipolis, 2008. http://tel.archives-ouvertes.fr/tel-00312718.
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Dans cette thèse, nous présentons une recherche expérimentale détaillée des lois caract érisant la taille et la densité atomique de grands pièges magnéto-optiques contenant typiquement 10^10 atomes. Il est bien connu que les interactions induites par laser, produites par la diffusion multiple, y constituent la limitation principale à l'obtention de densités atomiques élevées. Pour contourner cette limite, nous avons réalisé un piège magnéto-optique 'noir' combiné un piège dipolaire. Les forces de répulsion assistées par la lumière ont ainsi pu être considérablement réduites et une augmentation de près de deux ordres des grandeur sur le densité (jusqu'à 10^12 atm/cm^3) a été corrélativement observée. Nous avons proposé également un modèle qualitatif pour rendre compte de la densité atomique (et également pour la taille) o`u nous avons introduit les interactions mécaniques induites par les photons du laser repompeur quand son épaisseur optique devient importante. Ce travail fait partie d'un projet de recherche qui vise à terme à observer la localisation d'Anderson de la lumière dans des nuages d'atomes froids, mais pour laquelle des densités de l'ordre (10^13-10^14 atm/cm^3) sont requises. Pour des densités inférieures, des mécanismes de gain peuvent toutefois être mis à profit pour amplifier des modes pre-localisés. Nous avons, ainsi, mis en place une technique pompe-sonde pour la création d'un gain dans l'échantillon atomique. La configuration des pompes a autorisé l'observation du signal de mélange a quatre ondes. Une analyse détaillée de ses propriétés et de ses caractéristiques a été présentée. En particulier, une asymétrie rouge-bleu dans le spectre, pour des intensités élevées des faisceaux pompes, a été mise en évidence. Cette asymétrie a pu tre expliquée en tenant compte du regroupement des atomes dans les noeuds ou dans les ventres de l'onde stationnaire des faisceaux de pompe.
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Mancini, Marilia Wellichan. "Perdas colisionais devido ao processo de mudança de estrutura fina em uma armadilha magneto-óptica de rubídio." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-11092007-110102/.
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Observamos neste trabalho o processo de mudança de estrutura fina em colisões entre átomos de 85Rb resfriados e aprisionados em uma armadilha magneto-óptica. Medimos, através da fotoionização de fragmentos atômicos gerados nessas colisões, as taxas segundo as quais os átomos deixam a armadilha induzidos por esse processo colisional. Realizamos estudos das taxas de perda com relação a intensidade do laser de aprisionamento e com a freqüência, utilizando para isso a técnica de catálise. Nossos resultados indicam que a contribuição do processo de mudança de estrutura fina para a taxa de perdas total não é dominante. Constatamos que a estrutura hiperfina desempenha um papel importante na dinâmica colisional e na determinação dos valores das taxas. Interpretamos nossos resultados através de um modelo semi-clássico, sendo que este foi incapaz de explicar todos os efeitos observados. Propusemos algumas explicações qualitativas para as discrepâncias observadas. Acreditamos que nossos resultados devam servir de estímulo para novos trabalhos teóricos nesta área.We report the observation of trap-loss collisional rates due to fine structure changing collisions between cold and trapped 85Rb atoms. We have measured, by photoionization of the atomic fragments in 5P1/2 state originated in these collisions, the rates through the atoms leave the trap induced by this loss mechanism. We carried out experiments to determine the rate dependence with the intensity of the trapping laser, and with the frequency, using the catalisys technique. We also measured the contribution of this process to the total trap-loss rate and determined that fine structure changing is not the dominant loss mechanism. It was also observed that the hyperfine structure plays an important role in the rate behavior. We compared our results with those given by a semiclassical theoretical approach, the Gallagher-Pritchard model, and some disagreements were observed. We proposed some arguments to explain these discrepancies. We believe that such results should stimulate theoretical work on this field.
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Milori, Debora Marcondes Bastos Pereira. "Caracterização de uma armadilha magneto-optica para átomos de sódio em célula de vapor." Universidade de São Paulo, 1994. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-30042009-090336/.
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Dentro as técnicas de controle do movimento atômico utilizando pressão de radiação, aprisionamento tem merecido maior destaque por produzir amostras de átomos mais frios (temperaturas da ordem de μK), com altas densidades e confinadas em pequenas regiões do espaço. Devido a essas motivações, tem sido grande o esforço para desenvolver e caracterizar estas armadilhas atômicas. Uma das mais eficientes armadilhas de átomos neutros construídas até agora é a armadilha magneto-óptica. O átomo uma vez capturado por este tipo de armadilha passa por um intenso processo de desaceleração via efeito Doppler e acaba por ficar confinado no poço de potencial gerado pela interação com o campo magnético. O número e a densidade de átomos aprisionados, o tamanho da nuvem e o processo de carga possuem forte dependência com os parâmetros da armadilha, tais como: Este trabalho trata da caracterização de uma armadilha deste tipo para átomos de sódio através de um estudo sistemático para descobrir as condições de sua melhor performance. Paralelamente a este estudo, desenvolvemos modelos teóricos para entender em detalhe os processos de produção dessas nuvens de átomos aprisionados e as forças envolvidas neste tipo de material que é esse gás super resfriado.Among the various atomic motion control techniques using radiation pressure magneto-optic trapping has been looked at with great enthusiasm because it produces samples of cold atoms (temperatures about μK), with high densities and confined in small regions of space. Due to these motivations the efforts for developing and characterizing these atoms traps has been high. Once the atom is captured by the magneto-optic trap, it goes through an intense process of desacceleration via Doppler Effect and ends up confined in the potential well genered by the interaction with the magnetically Field. The number and the density of the trapped atoms, the size of the cloud and the loading process are strongly related to trap parameters, such as: magnetic Field gradient, laser beam intensity and background vapor temperature. This work deals with the characterization of a trap of this kind for sodium atoms through a systematic study, in order to discover the conditions for a better performance. At the same time theoretical models are developed in order to understand in depth the atomic forces involved in the production of a new kind of material which is this highly refrigerated gas.
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Silva, Ilde Guedes da. "Estruturas espaciais de átomos de Na em armadilha magneto-óptica." Universidade de São Paulo, 1994. http://www.teses.usp.br/teses/disponiveis/54/54131/tde-21022014-101849/.
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Neste trabalho demonstramos o confinamento de átomos de sódio usando a armadilha magneto-óptica, onde os átomos foram capturados diretamente a partir da distribuição inicial do vapor atômico a uma temperatura ambiente, contido em uma célula fechada. Observamos além da nuvem de átomos aprisionados, estruturas circulares em forma de anek, que surgem devido ao desalinhamento introduzido nos feixes de aprisionamento. Estudamos o comportamento do raio do anel em função de vários parâmetros utilizados na armadilha magneto-óptica como por exemplo: gradiente de campo magnético, intensidade do laser, dessintonia e desalinhamento. Os experimentos foram realizados no regime de baixa densidade (N<10s) onde o raio do anel é independente do número de átomos aprisionados. Assim, os resultados obtidos podem ser explicados utilizando um modelo simples que leva em conta a força de vórtice dependente da coordenada radial (ou macroscópica) e as forças usuais presentes na armadilha magneto-ópticaIn this work we demonstrate the confinement of neutral sodium atoms using the magneto-optical trap, where the atoms were captured directly from the low velocity tail of the room-temperature atomic vapor contained in the closed vacuum cell. We observed besides the cloud shaped, circular structures like a ring of trapped atoms that apeears when we introduce a misalignment among the trapping beams. We studied the behavior of ring radius with respect to several trapping parameters as: magnetic-field gradient, laser intensity, detuning, and misalignment. The experiments were performed in the low density regime (N<10s), so the ring radius is independent of the number of trapped atoms. Hence, the results obtained can be explained using a simple model that takes into account a radial coordinate dependent (or macroscopic) vortex force and the usual magneto-optical trap forces
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Glover, Rohan David. "Atomic and optical Collisions with Cold Metastable Neon." Thesis, Griffith University, 2012. http://hdl.handle.net/10072/367016.
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This thesis presents investigations into the collision dynamics of cold metastable neon atoms in a magneto-optical trap (MOT). At very cold temperatures (approx. 1 mK) the atomic interaction occurs at long range and cannot be treated classically as the interaction between two nuclear point particles. In addition, the collision dynamics can be considerably altered in the presence of an optical eld. In this thesis results are presented for collisions that are altered by the presence of an optical eld and also collisions where the optical eld can be neglected. Controlled optical collisions of cold, metastable Ne atoms are performed by using a control laser tuned close to the (3s)3P2 to (3p)3D3 cooling transition. The control laser modies the rate of ionizing collisions by promoting a pair of colliding atoms onto an excited state potential. In order to induce collisions between pairs of trapped metastables, a control laser is tuned to the red of the transition where we measure a factor of 4 increase in the rate for ionizing collisions. We also investigate the eect of optical shielding by tuning the laser to the blue of the transition and observe a factor of 5 suppression in the ionization rate. However, the measured ionization spectrum does not contain resonances
due to the formation of photoassociated molecules as predicted by Doery et al [1]. Instead, we observe a broad unresolvable ionization spectrum that is well described by established theory [2]. Collision cross sections are measured for neon in the (3s)3P2 metastable state with ground state, thermal atoms and molecules. The technique is based on the measurement of the loss rate due to collisions with a background gas. Generally, these type of collisions are considered undesirable, however, it is possible to infer information about the collision cross section if the rate of collisions is accurately known. This novel technique is described
and collision cross section measurements are presented for metastable neon in the (3s)3P2 state with He, Ne, Ar, H2, O2, and N2. The average thermal energy of the collision ranges from 11 meV to 27 meV and the measurements have relatively small errors, of the order of 10%.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Science, Environment, Engineering and Technology
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Matherson, Kristen Joy. "Laser Cooling Trapping of Metastable Neon and Applications to Collision Measurements." Thesis, Griffith University, 2010. http://hdl.handle.net/10072/367097.
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This thesis presents a new technique for measuring total absolute collision cross sections.
Using this technique, the total absolute collision cross sections were determined
for neon in the (3s)3P2 metastable state with ground state thermal atoms
and molecules. A magneto-optical trap (MOT) is used in this technique which infers
the cross sections via the measurement of population dynamics within the MOT to
determine the collision cross section.
This technique is capable of providing benchmark measurements of total absolute
collision cross sections. The measurements are unique for the low average collision
energy which ranges between 11meV and 27meV for the dierent collision species and
relatively low uncertainty of approximately 9.4%. The measurements were for neon
in the (3s)3P2 metastable state with He, Ne, Ar, H2, O2, N2 and CO2. The measured
cross sections were respectively 160±20Å2, 500±50Å2, 840±80Å2, 230±20Å2, 1000±100Å2, 1300.0±100Å2, 830±80Å2. The measurements made using this technique have small uncertainties, of the order of 10% of the measured cross section.
As Ne* does not have the energy to ionize He, the Ne*-He collision was entirely elastic
and the validity of this technique was conrmed by comparing the experimental result
for this collision with an approximation for the elastic collision cross section based on
van der Waals forces. The calculation based on this approximation yielded an elastic
cross-section of 168.88Å2 for the Ne*-He system. This theoretical value compared
favourably and within the uncertainties of the experimental measurement for the
Ne*-He collision of 160±20Å2.
To be able to perform these investigations a rebuild and partial redesign of the Griffith
University metastable neon trapping apparatus was necessary and was included in this
work.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Science, Environment, Engineering and Technology
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Paul, Justin Reiford. "Construction and Characterization of a Neutral Hg Magneto-Optical Trap and Precision Spectroscopy of the 6¹S₀ - 6³P₀ Hg¹⁹⁹ Clock Transition." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/565889.
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In this dissertation I present theory and experimental results obtained in the Jones research group at the University of Arizona investigating the feasibility of neutral Hg as a candidate for an atomic clock. This investigation includes laser-cooling and trapping of several neutral Hg isotopes as well as spectroscopy of the 6¹S₀ - 6³P₀ doubly forbidden clock transition in neutral Hg¹⁹⁹. We demonstrate precision spectroscopy of the ground state cooling/trapping transition of neutral mercury at 254 nm using an optically pumped semiconductor laser (OPSL). This demonstration exhibits the utility of optically pumped semiconductor lasers (OPSLs) in the field of precision atomic spectroscopy. The OPSL lases at 1015 nm and is frequency quadrupled to provide the trapping light for the ground state cooling transition. We get up to 1.5 W single-frequency output power having a linewidth of < 10 kHz in the IR with active feedback. We frequency quadruple the OPSL in two external cavity stages to produce up to 120 mW of deep-UV light at 253.7 nm. I give a detailed characterization of the construction and implementation of the neutral Hg vapor cell magneto-optical trap (MOT). The trap can be loaded in as quickly as 75 ms at background vapor pressures below 10⁻⁸ torr. At reduced background pressure (< 10⁻¹⁰ torr) the loading time approaches 2 sec. We describe construction and stabilization of a laser resonant with the Hg¹⁹⁹ clock transition and the methods employed to find and perform the experimentally delicate spectroscopy of the clock transition. We present experimental results and analysis for our initial spectroscopy of the 6¹S₀- 6³P₀ clock transition in the Hg¹⁹⁹ isotope of neutral mercury.
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Paul, Justin Reiford. "Construction and characterization of a neutral Hg magneto-optical trap and precision spectroscopy of the 61S 0 - 63P0 Hg199 clock transition." Thesis, The University of Arizona, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3717608.
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In this dissertation I present theory and experimental results obtained in the Jones research group at the University of Arizona investigating the feasability of neutral Hg as a candidate for an atomic clock. This investigation includes laser-cooling and trapping of several neutral Hg isotopes as well as spectroscopy of the 61S0 - 6 3P0 doubly forbidden clock transition in neutral Hg199.
We demonstrate precision spectroscopy of the ground state cooling/trapping transition of neutral mercury at 254 nm using an optically pumped semiconductor laser (OPSL). This demonstration exhibits the utility of optically pumped semiconductor lasers (OPSLs) in the field of precision atomic spectroscopy. The OPSL lases at 1015 nm and is frequency quadrupled to provide the trapping light for the ground state cooling transition. We get up to 1.5 W single-frequency output power having a linewidth of <10 kHz in the IR with active feedback. We frequency quadruple the OPSL in two external cavity stages to produce up to 120 mW of deep-UV light at 253.7 nm.
I give a detailed characterization of the construction and implementation of the neutral Hg vapor cell magneto-optical trap (MOT). The trap can be loaded in as quickly as 75 ms at background vapor pressures below 10-8 torr. At reduced background pressure (<10-10 torr) the loading time approaches ∼2 sec.
We describe construction and stabilization of a laser resonant with the Hg199 clock transition and the methods employed to find and perform the experimentally delicate spectroscopy of the clock transition. We present experimental results and analysis for our initial spectroscopy of the 61S0 - 63 P0 clock transition in the Hg199 isotope of neutral mercury.
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Daily, Jared Estus. "Two-Photon Ionization of the Calcium 4S3D 1D2 Level in an Optical Dipole Trap." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd713.pdf.
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Peñafiel, Edwin Eduardo Pedrozo. "Absorção cooperativa de dois fótons em átomos frios." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-04102011-155751/.
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Neste trabalho estudamos a absorção cooperativa de dois fótons em processos de colisão entre átomos frios de sódio aprisionados. Efeitos não-lineares exigem amostras de alta densidade para ser observados. Redesenhamos nosso sistema experimental para conseguir amostras de 1012 átomos/cm3. As principais alterações foram a construção de um desacelerador Zeeman em configuração spin-flip, a implementação de bombeamento diferencial entre o forno e a câmara principal, assim como redesenhar o forno. A fim de compreender e melhorar os processos de medição utilizamos a técnica de fotoionização nos estados 32P1/2 e 32P3/2. Com esses dados conseguimos calcular a seção transversal de ionização para cada um desses estados, que está de acordo com valores reportados na literatura. Estes resultados mostram que o novo desenho do sistema permite um grande ponto de partida para a medição da absorção de dois fótons. Uma tentativa de medir a absorção de dois fótons foi feita. Um pequeno aumento no número de íons produzidos por unidade de tempo foi observada em uma região deslocada para o vermelho de cerca de 4,5 GHz de onde inicialmente se esperava ocorrer a transição. Isto motiva a aprofundar o estudo da absorção de dois fótons, já que provavelmente essa medida seja um indício da ocorrência desse fenômeno. Assim, tanto a medição da seção de choque dos estados 32P1/2 e 32P3/2 e a tentativa de medir a absorção de dois fótons, fornecem uma base sólida para conhecer qual é a melhor maneira de obter resultados mais decisivos no que diz respeito à absorção cooperativa de dois fótons, e as vantagens do nosso sistema em futuros experimentos.In this work we study the cooperative two-photon absorption in collisional processes between cold trapped sodium atoms. Nonlinear effects require high density samples to be observed. We redesign our experimental system to achieve samples up to 1012 atoms/ cm3 .The key changes were building a spin-flip Zeeman slower, implementing differential pumping between the oven and the chamber and changing the oven´s design. In order to understand and improve the measurement processes we did photoionization from the states 32P1/2 e 32P3/2. With this data we could calculate the ionization cross section for each of these states, which is in agreement with values reported in the literature. These results show that the new design of the system allows a great starting point for measuring of two-photon absorption. An attempt to measure the absorption of two-photon was made. A small increase in the number of ions produced per unit time was observed in a region shifted to the red of about 4.5 GHz from where we initially expected the transition to occur. This probably indicates two-photon absorption. Thus, both the measurement of cross section of states and the attempt to measure the absorption of two photons, provide a solid foundation for understanding what is the best way to obtain more decisive results with regard to cooperative absorption, and the advantages of performance of our system in future experiments.
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Fritsch, Amilson Rogelso. "Montagem e caracterização de uma armadilha magneto-óptica de rubídio." Universidade do Estado de Santa Catarina, 2011. http://tede.udesc.br/handle/handle/2008.
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In this work we present the building and characterization of a Magneto-Optical Trap (from now on named MOT) for Rubidium atoms. We perform experiments for studying the e¤ect of a broadband light over trapped atoms. In order to carry out this study we used a incandescent lamp which is broad in the wavelength spectrum. We observed in a MOT, with a number of 109 trapped atoms, that the broadband light increases the emitted .uorescence by the cloud of atoms. This could indicate an e¤ective enlargement in the trap e¢ciency. However, we cannot distinguish, based on our experiments, if this di¤erence is due to an increasing in the number of the trapped atoms or if it is just scattered light caused by the increasing in the intensity of the incident light over the cloud. Thus, we did an analysis in the answer of the laser beam versus the variation in the intensity of lasers used for trapping. In a second step, we perform this study but with a lower number of trapped atoms, 108 atoms, and we verify that the heating of the lamps implies in the increasing of the loss of atoms in the trap, diminishing the number of trapped atoms. Hence, this lead us to make a study on the collisions dynamics that are in the trap, in order to understand the in.uence of the temperature on the trap e¢ciency. We observe that a small uniform increasing in the chamber temperature would lead to a great loss in the trap , but the increasing in the temperature caused by the lamps is a local increasing and generates a degassing of the chamber, increasing the quantity of the background vapour.
Neste trabalho apresentamos a construção e caracterização de uma armadilha magneto-óptica, a qual utilizamos para aprisionamento de átomos de Rb. Após a construção da armadilha e sua caracterização, fizemos experimentos para estudar os efeitos da luz de banda larga sobre os átomos aprisionados. Para esse estudo, utilizamos lâmpadas incandescentes que possuem um espectro largo de comprimentos de onda. Verificamos que em uma armadilha com 109 átomos aprisionados, a luz de banda larga aumenta a fluorescência emitida pela nuvem de átomos, tendo fortes indícios que isto representa efetivamente um aumento na eficiência da armadilha. No entanto, com os experimentos que fizemos, não podemos distinguir se essa diferença é referente a um aumento de átomos aprisionados ou apenas espalhamento de luz causado pelo aumento da intensidade de luz incidida sobre a nuvem. Fizemos então uma comparação da resposta dos átomos, frente a variações na intensidade dos feixes de laser utilizados para o aprisionamento. Por motivos que serão discutidos neste trabalho, refizemos esse estudo com um número menor de átomos aprisionados, 108 átomos, e verificamos que o aquecimento das lâmpadas reflete no aumento das perdas na armadilha, diminuindo então o número de átomos aprisionados. Isto nos levou a fazer um estudo sobre a dinâmica das colisões presentes na armadilha, para entendermos a influência da temperatura na eficiência da armadilha. Verificamos que um pequeno aumento uniforme na temperatura da câmara levaria a grandes perdas na armadilha, mas o aumento da temperatura causado pelas lâmpadas é um aumento local, e gera um processo de desgaseificação da câmara, aumentando a quantidade de átomos, "diferentes de Rb", presentes no vapor de fundo.
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Agomuo, John Chidowerem. "Excitation and photoionization of laser-cooled atoms in the AC-driven magneto-optical trap (AC-MOT), using resonant and non-resonant radiation." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/excitation-and-photoionization-of-lasercooled-atoms-in-the-acdriven-magnetooptical-trap-acmot-using-resonant-and-nonresonant-radiation(1e69ad21-035e-4fc5-a3a5-80a7943e7641).html.
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Results of experiments involving the manipulation of atoms using laser radiation are presented. A high-density trap of potassium atoms was created using an AC-driven magneto-optical trap (AC-MOT), loaded from a Zeeman-slowed atomic beam. The AC-MOT was operated in a pulsed mode, with a trapping laser that was detuned by -4Γ, where Γ is the natural line-width of the trapping transition. Under these conditions, the AC-MOT trapped an average of 3.63±0.02×〖10〗^8 atoms, which were cooled to a mean temperature of 275μK±33μK.Using the AC-MOT, the absolute photoionization cross-section of cold potassium atoms was determined using ionizing laser radiation at 450.4 nm obtained from a high-power diode laser. The measured photoionization cross-section from the 42P3/2 excited state was obtained by measuring the loss rate and the lifetime of the AC-MOT during the loading and decay processes. Using these methods, the cross section was determined to be 1.49±0.13 Mb, and 2.38±0.18 Mb respectively. Precise energy levels of high-n Rydberg states of potassium have also been measured using stepwise-excitation of the trapped atoms, with the intermediate state being the 42P1/2 state that was excited by resonant laser radiation at 389,286,368.12 MHz. Excitation from the 42P1/2 state to the n^2 S_(1/2) states was carried out using blue radiation from a dye laser, for transitions to Rydberg states with principal quantum numbers ranging from n = 18 to ~200. For excitation to the n^2 D_(3/2) states, transitions up to Rydberg states with n ranging from 18 to 167 were studied. Due to the strong interaction between Rydberg atoms, the measured energy levels deviated from their predicted theoretical values at high principal quantum numbers (n≥130 for the S-states, and n≥100 for the D-states). For principal quantum numbers greater than these values, the spectral lines were found to both broaden and shift in energy, and new features in the Rydberg spectra were observed. These new features have been attributed to the dipole-forbidden n2P1/2 and n2P3/2 states, which cannot be excited directly by the laser. These states must hence be excited due to interplay between the highly excited Rydberg atoms that is occurring due to their large effective size and close proximity in the AC-MOT.
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Souther, Nathan Jon. "Light Shift Measurements of Cold Rubidium Atoms using Raman Pump-Probe Spectroscopy." Miami University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=miami1250622906.
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Agyare, Benjamin A. "INVESTIGATION OF ATOMIC MOTION IN OPTICAL LATTICES VIA INTENSITY CORRELATION MEASUREMENT." Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1186171967.
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Pereira, Andrea Antunes. "Estudo de colisões inelásticas heteronucleares no sistema rubídio(Rb)/césio(Cs) em regimes de baixas temperaturas." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-09092008-123340/.
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Armadilhamento duplo de átomos neutros constitui um dos avanços mais recentes no estudo de colisões frias. Obtivemos experimentalmente as taxas de perda devido a interação de espécies alcalinas mistas (Cs/Rb). Utilizamos uma armadilha magneto-óptica mista operando com feixes de alta intensidade permitindo o resfriamento e confinamento das amostras com sucesso. Esse trabalho apresenta-se de forma relevante pois corresponde a primeira etapa para o estudo do processo de formação de moléculas frias heteronucleares. Uma comparação entre duas técnicas de monitoramento dos processos de carga de átomos foi realizada. Os resultados tanto qualitativamente como quantitativamente foram satisfatórios. Determinamos as taxas de perda, de interesse e analisamos essas taxas considerando a proporção entre as massas dos átomos envolvidos e enfocando o efeito causado pela diferença de massa entre eles concluindo assim o objetivo principal dessa dissertação.Double trapping of neutral atoms is one of the most recent advances in the study of collisions cold. Experimentally obtained the rates of loss due to the interaction of species alkaline mixed (Cs / Rb). We use a magneto-optical trap mixed operating with beams of high intensity allowing the cooling and containment of the samples successfully. This work is so important because it represents the first step to study the process of formation of molecules heteronucleares cold. A comparison between two techniques of monitoring procedures for cargo of atoms was performed. The results both qualitatively and quantitatively were satisfactory. And the rates of loss of interest and analyze the rates considering the ratio between the masses of atoms involved and focusing on the effect caused by the difference of mass between them thus completing the main objective of this dissertation.
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Magalhães, Kilvia Mayre Farias. "Obtenção da degenerescência quântica em sódio aprisionado." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-24012008-083710/.
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Usando a técnica de resfriamento evaporativo para átomos comprimidos numa armadilha magnética tipo QUIC, implementamos experimentos para observar Condensação de Bose-Einstein de átomos de sódio. Nessa armadilha magnética temos átomos advindos de uma armadilha magneto-óptica, a qual é carregada por um feixe desacelerado como etapa de pré-resfriamento. Nossas medidas foram baseadas em imagens de absorção fora de ressonância de um feixe de prova pela amostra atômica. Essas imagens foram feitas in situ, ou seja, na presença do campo da armadilha magnética, pelo fato do número de átomos ser baixo e a técnica de tempo de vôo não ser adequada a essa situação. Baseado no perfil de densidade e na temperatura medidos, calculamos a densidade de pico no espaço de fase D, a qual é seguida nas várias etapas de evaporação. Nossos resultados mostram que para uma freqüência final de evaporação de 1,65 MHz nós superamos o valor esperado para D (2,612) alcançar o ponto crítico, no centro da amostra, para obter a condensação. Devido ao baixo número de átomos restantes no potencial, a interação não produz efeitos consideráveis e dessa forma um modelo de gás ideal permite justificar essa observação.Using a system composed of a QUIC trap loaded from a slowed atomic beam, we have performed experiments to observe the Bose-Einstein Condensation of Na atoms. In order to obtain the atomic distribution in the trap, we use an in situ out of resonance absorption image of a probe beam to determine the temperature and the density, which are use to calculate the phase space D. We have followed D as a function of the final evaporation frequency. The results show that at 1.65 MHz we crossed the critical value for D which corresponds to the point to start Bose-Condensation of the sample. Due to the low number of atoms remaining in the trap at the critical point, the interaction produce minor effects and therefore an ideal gas model explains well the observations.
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ALVAREZ, Ammis Sánchez. "Armadilha magneto ótica de rubídio e mistura de quatro ondas no vapor atômico." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18556.
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Facepe
Neste trabalho apresentamos a caracterização de uma armadilha magneto ótica de átomos de Rb construída em nosso laboratório, juntamente com o seu princípio de funcionamento. O resfriamento é feito com lasers de diodo e tem como mecanismo básico a força de pressão de radiação, que é gerada pelos processos de absorção e emissão de fótons, juntamente com a ação de um campo magnético e a polarização dos feixes. O sistema consiste em três pares de feixes contrapropagantes nas direções x, y e z, com polarizações s+ e s, e um campo magnético que varía linearmente no espaço. Conseguimos armadilhar aproximadamente 108 átomos com um tempo de carga da ordem de 2 seg. Em paralelo realizamos medidas de mistura de quatro ondas degenerada em um vapor de átomos de Rb, na configuração de feixes quase-copropagantes. O sinal gerado no processo não linear foi estudado em função da frequência de um dos feixes enquanto o outro tinha sua frequência fixa; e se mostrou independe de qual dos feixes esta sendo sintonizado. Medidas simultâneas da transmissão do feixe de prova indicam que o processo não linear ocorre só na transição cíclica e envolve o grupo de átomos selecionados pelo feixe de frequência fixa.
In this work we present a characterization of magneto optical trap of 87Rb atoms built in our lab, along with its operating principle. The cooling is done with a diode laser and its basic mechanism is the force of radiation pressure, which is generated by the processes of absorption and emission of photons, together with the action of a magnetic field and polarization of the beams. The system consists of three pairs of counterpropagating beams in the x, y and z directions with s+ and s polarizations, and a magnetic field that varies linearly in space. We were able to trap about 108 atoms with a charging time of approximately 2 sec. In parallel we performed degenerate four wave mixing measures in a Rb vapor atoms using a quasi-copropagating beams configuration. The signal generated in the nonlinear process was studied as a function of one of laser’s while keep the other with a fixed frequency; and it showed independent of which of the beams is being tuned. Simultaneous measurements of the transmission of the probe beam indicates that the nonlinear process occurs only in the cyclic transition and involves the group of atoms selected by the beam with fixed frequency.
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Magalhães, Kilvia Mayre Farias. "Medida do tempo de vida de estados de Rydberg em átomos frios de 85 Rb." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-21112007-100629/.
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Neste trabalho apresentamos os primeiros resultados sobre medida do tempo de vida de estados de Rydberg utilizando átomos frios confinados em uma armadilha magneto-optica de 85Rb. Medidas de tempo de vida de estados altamente excitados são importantes para o teste de teorias modernas sobre interação átomo-vácuo; desta forma medidas precisas são necessárias. A utilização de átomos frios apresenta várias vantagens quando comparadas com técnicas convencionais. Entre elas podemos citar a possibilidade de observação do sistema atômico por longos períodos (>100 µs), e o controle da densidade de forma eficiente para evitar a manifestação de efeitos indesejáveis (colisões, superradiância) que limitam a precisão da medida. Apresentamos a medida do tempo de vida do estado 27D e 38S e comparamos os resultados experimentais com previsões teóricas de diferentes modelos. Algumas discrepâncias são observadas, o que reforça a necessidade da obtenção de um conjunto maior de medidas incluindo outros níveis para indicar qual modelo teórico é mais próximo da realidade.In this work we present our first results on lifetime measurement of Rydberg states using cold atoms held in a magneto-optical trap of 85Rb. Lifetime measurements of highly excited states are important for testing modern theories on atom-vaccum interaction, therefore precise measurements are required. The use of cold atoms presents some advantage when compared with conventional techniques. Among them we cam point out the possibility of atomic observation for long periods of time (<100 µs), the atomic density control in order to avoid undesired effects (such collisions and superradiance) which can limit the measurement precision. We present the lifetime measurement of 27D and 38S states and compared the experimental results with theoretical prediction using different models. Some discrepancies are observed, which indicates the need of a large set of measurement for other states in order to indicate the best model.
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Jackson, Jarom Silver. "In Situ Magnetic Field Characterization with the Directional Hanle Effect." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/5982.
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We present a novel method of in situ magnetic field mapping related to the Hanle effect. This method uses the change in spatial radiation pattern of scattered light, which we call a 'directional Hanle effect,' rather than the loss of polarization more commonly associated with the Hanle effect. It is particularly well suited for fields in a magneto-optical trap (MOT), requiring only the addition of a narrow slit and a camera to typical MOT components. The use of this method is demonstrated by measuring the gradient through, and location of, the zero-point of the field in our strontium MOT.
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Hommelhoff, Peter. "Bose-Einstein-Kondensate in Mikrochip-Fallen." Phd thesis, [S.l.] : [s.n.], 2002. http://edoc.ub.uni-muenchen.de/archive/00000702.
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Muniz, Sérgio Ricardo. "Estudo de Blindagem Óptica em Colisões Frias." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-06052005-162937/.
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Neste trabalho, mostramos que é possível suprimir a maioria dos processos inelásticos que podem causar perdas de átomos em armadilhas magneto-ópticas. Nossos resultados revelam que o processo de blindagem óptica (demonstrado pelo nosso grupo, pela primeira vez para o processo de ionização fotoassociativa Phys. Rev. Lett. 73, 1911 (1994)) é bem mais geral do que se supunha. Permitindo, inclusive, a supressão de colisões entre átomos no estado fundamental. E provavelmente qualquer outro processo inelástico que ocorra a curtas distâncias internucleares. Para se chegar a esses resultados, foi necessário desenvolver uma nova técnica de aprisionamento, que permite o estudo de colisões frias, mesmo em armadilhas cujo potencial de confinamento é pequeno. Graças a essa técnica foi possível, pela primeira vez, observar perdas causadas por mudança de estrutura hiperfina, numa armadilha de átomos de sódio operando na linha D1 (carregada a partir de uma célula de vapor). Essa técnica ainda nos permitiu medir a taxa de colisões frias () no trap da linha D1, um dado que até então não existia na literatura. Para verificar a confiabilidade dos resultados obtidos por essa técnica, realizamos também medidas de na linha D2 e comparamos esses resultados com outros existentes na literatura (obtidos por uma técnica diferente). A boa concordância entre esses resultados nos deixa confiantes em dizer que essa técnica, além de ser muito interessante, no estudo de armadilhas rasas (seja isso devido à intensidade dos lasers de aprisionamento, seja devido a natureza própria da armadilha), é também bastante confiávelIn this work, we showed that is possible to suppress most of the inelastic processes that may cause losses of atoms in a magneto-optical trap. Our results reveal that the process of optical shielding (demonstrated by our group, for the first time to photoassociative ionization - Phys. Rev. Lett. 73, 1911 (1994)) is much more general than it was supposed. Even allowing the suppression of ground state collisions and probably any other inelastic process that happens at short internuclear distances. To achieve those results, it was necessary to develop a new trapping technique, which allows the study of cold collisions, even in traps whose confinement potential is small. Thanks to that technique it was possible, for the first time, to observe losses caused by hyperfine changing collisions, in a trap of sodium atoms operating in the D1 line (loaded from a vapor cell). That technique has still allowed us to measure the rate of cold collisions () for the D1 line trap, a result which, until now, did not exist in the literature. To verify the reliability of the results obtained by that technique, we also accomplished measures of in the D2 line and compared those results with other existent ones in the literature (obtained by a different technique). The good agreement among those results, made us confident in saying that this technique, besides being very interesting in the study of shallow traps (due to the intensity of the trapping lasers, or due to the own nature of the trap), it is also quite reliable.
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Mancini, Marília Wellichan. "Produção de moléculas frias heteronucleares no estado fundamental." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-06062007-184808/.
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Neste trabalho apresentamos a produção de moléculas frias heteronucleares em uma armadilha magneto-óptica mista de 39K e 85Rb e detectadas no estado fundamental. A técnica de detecção consiste na fotoionização pulsada das moléculas que, após terem sido fotoassociadas, decaem através de emissão espontânea para estados ligados do potencial do estado molecular fundamental. A partir dos resultados da produção de moléculas frias KRb, estudamos-as com relação ao tipo de colisões que as originam, e à temperatura associada ao seu movimento translacional. Experimentos foram também realizados para comprovar que as moléculas detectadas são provenientes do estado fundamental. Finalmente, também estudamos neste trabalho, a taxa segundo a qual são formadas. Concomitantemente à produção de KRb, moléculas frias homonucleares 39K2 e 85Rb2 são também formadas, detectadas e caracterizadas. São apresentados também, os primeiros passos dados em direção à realização de espectroscopia fotoassociativa dos estados ligados das moléculas heteronucleares obtidas.In this work, cold ground-state KRb molecules were produced by photoassociation in a two species magneto-optical trap (MOT) containing 39K and 85Rb. The KRb molecules are produced through photoassociation and detected in the ground state by multiphoton pulsed ionization. We have characterized their translational temperature and measured their formation rate constant. Homonuclear cold molecules 39K2 and 85Rb2 detected in their ground state were also formed in our trap and characterized as well. It is also reported our first efforts towards the realization of photoassociation spectroscopy of the heteronuclear molecules produced in our trap.
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Corrêa, Thiago Reginaldo. "Implicações do uso de campos magnéticos oscilantes em um mot de rubídio." Universidade do Estado de Santa Catarina, 2012. http://tede.udesc.br/handle/handle/1969.
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This work presents a study about infuences that a quadripolar magnetic field periodically time dependent, can promote in a magneto-optical trap (MOT). The intention reflects the interest in finding an oscillating field configuration that enables the capture and provide benefits if compared to the typical process of trapping. In many papers that will be cited here, a MOT uses a magnetic field that promotes a linear steady magnetic field gradient from the center of the trap. Applying experimental results involving magnetic field oscillations, which will be quoted in detail throughout this text, came the initiative to mathematically model the problem and seek a form of oscillation that may result in a more efficient trapping. Numerical results in a one-dimensional model suggests that the number of atoms is strongly aflected by fuctuations, but we have not found, for the modulations suggests in this work, an oscillation model that could provide an increase of the trap atoms. It was noted that the oscillation frequency of the atom is subjected, aflect the amplitude of the oscillations in the number of trapped atoms.
Neste trabalho apresentamos um estudo sobre as influências que um campo quadripolar magnético, periodicamente dependente do tempo, pode promover em uma armadilha magnético-óptica (Magneto Optical Trap - MOT). O objetivo deste trabalho reflete o interesse em encontrar uma configuração de campo oscilante que possibilite o aprisionamento e forneça vantagens em relação ao processo típico de armadilhamento. Em muitos dos trabalhos que serão citados aqui, um MOT utiliza um campo magnético quadripolar estacionário que promove um gradiente de campo magnético linear à partir do centro da armadilha. Usando resultados experimentais envolvendo oscilações no campo magnético, que serão citados mais detalhadamente no decorrer deste texto, surgiu a iniciativa de modelar o problema matematicamente e buscar uma forma de oscilação que possa resultar em um aprisionamento mais eficiente. Resultados numéricos concebidos em um modelo unidimensional sugerem que o número de átomos é fortemente afetado pelas oscilações, mas não foi possível encontrar, para as modulações sugeridas neste trabalho, uma modulação que pudesse fornecer aumento expressivo no número de átomos armadilhados. Foi possível constatar que a freqüência da oscilação a que o átomo é submetido, afetará a amplitude das oscilações no número de átomos armadilhados.
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Ashmore, Jonathan P., and n/a. "Laser Cooling and Trapping of Metastable Neon and Applications to Photoionization." Griffith University. School of Science, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060202.153538.
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This thesis presents an in-depth study into the characterization and enhancement of a metastable neon laser cooled and trapped atomic beam. The apparatus consists of a standard Zeeman slowed atomic beam loaded into a magneto-optical trap and was designed for applications to electron scattering experiments and photoionization. The efficiency of the metastable neon atomic source was investigated to determine the ideal cathode type for maximum metastable production and optimal atomic beam velocity haracteristics. A series of characterization measurements were performed on the MOT, and the trap volume and population were investigated for a range of trapping and slowing laser intensities and detunings, together with the MOT and Zeeman slower magnetic fields. The volume measurements were compared to standard Doppler theory and it was found that the Doppler model inadequately explained the trap behaviour. It was found that the MOT population characteristics were governed by two processes: two-body losses that limit the trap population at high densities, and the efficiency of the atom capture process which limits the operational range of the MOT over the various parameters. The trap temperature was determined to be 1.3mK via a time-of-flight technique. This was nearly twice that predicted by Doppler theory and the lack of agreement once again suggests the inadequacies in the Doppler theory to correctly model the experiment. The application of the MOT to the photoionization cross-section measurement of the (2p53p)3D3 state of neon was investigated. The MOT decay technique was utilized to measure cross-section values of o351 = 2.9+0.2 -0.3 x 10 -18cm2 and o363 = 3.1 +0.3 -0.4 x 10-18cm2 at the wavelengths of 351nm and 363nm respectively. This is an increase in accuracy of around a factor of five from previous measurements and it was found that the results agreed well with the values predicted by current theories.
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Ashmore, Jonathan P. "Laser Cooling and Trapping of Metastable Neon and Applications to Photoionization." Thesis, Griffith University, 2005. http://hdl.handle.net/10072/367728.
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This thesis presents an in-depth study into the characterization and enhancement of a metastable neon laser cooled and trapped atomic beam. The apparatus consists of a standard Zeeman slowed atomic beam loaded into a magneto-optical trap and was designed for applications to electron scattering experiments and photoionization. The efficiency of the metastable neon atomic source was investigated to determine the ideal cathode type for maximum metastable production and optimal atomic beam velocity haracteristics. A series of characterization measurements were performed on the MOT, and the trap volume and population were investigated for a range of trapping and slowing laser intensities and detunings, together with the MOT and Zeeman slower magnetic fields. The volume measurements were compared to standard Doppler theory and it was found that the Doppler model inadequately explained the trap behaviour. It was found that the MOT population characteristics were governed by two processes: two-body losses that limit the trap population at high densities, and the efficiency of the atom capture process which limits the operational range of the MOT over the various parameters. The trap temperature was determined to be 1.3mK via a time-of-flight technique. This was nearly twice that predicted by Doppler theory and the lack of agreement once again suggests the inadequacies in the Doppler theory to correctly model the experiment. The application of the MOT to the photoionization cross-section measurement of the (2p53p)3D3 state of neon was investigated. The MOT decay technique was utilized to measure cross-section values of o351 = 2.9+0.2 -0.3 x 10 -18cm2 and o363 = 3.1 +0.3 -0.4 x 10-18cm2 at the wavelengths of 351nm and 363nm respectively. This is an increase in accuracy of around a factor of five from previous measurements and it was found that the results agreed well with the values predicted by current theories.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Science
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Campestrini, Iara Maitê. "Estudo do efeito da dessorção atômica induzida por luz na dinâmica de carga de uma armadilha magneto-óptica de rubídio." Universidade do Estado de Santa Catarina, 2013. http://tede.udesc.br/handle/handle/1978.
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In order to increase the efficiency of magneto-optical traps, yielding a greater number of trapped atoms and long lifetimes, the effect of lightinduced desorption atom source emerges as an adjuvant and no thermal atoms. A prior experimental investigation (FRITSCH, 2011) showed that the number of rubidium atoms trapped increases when a light desorption focuses on the inner walls of the chamber imprisonment, whose material is stainless steel. The light desorption is applied from an incandescent lamp with power equal to 60 mW. The experimental data are adjusted and parameters are determined from the trap, in case of absence of light. Thus, the theoretical model proposed by Zhang et al. (2009) is applied, describing the increase of the number of atoms in the magneto-optical trap when the light desorption is triggered. In this setting, the rate of desorption and adsorption coefficient is estimated at 5x1017 atoms per second and 55 s-1. The combination of this model with that proposed by Monroe et al. (1990), in case of absence of light, perfectly describes the experimental curve generated when the mechanism for obtaining the magneto-optical trap and light desorption are actuated simultaneously. Furthermore, a theoretical prediction for the desorption rate, the rate of charging of magneto-optical trap and maximum number of atoms trapped on the basis of light desorption power is shown graphically.
Com o intuito de aumentar a eficiência das armadilhas magnéto-ópticas, obtendo-se um número maior de átomos aprisionados e longos tempos de vida, o efeito de dessorção atômica induzida por luz surge como uma fonte coadjuvante e não térmica de átomos. Uma investigação experimental prévia (FRITSCH, 2011) comprovou que o número de átomos de rubídio armadilhados aumenta quando uma luz de dessorção incide sobre as paredes internas da câmara de aprisionamento, cujo material é de aço inoxidável. A luz de dessorção aplicada é proveniente de uma lâmpada incandescente com potência igual a 60 mW. Os dados experimentais são fitados e os parâmetros da armadilha são determinados, para o caso sem luz. Com isso, o modelo teórico proposto por Zhang et al. (2009) é aplicado, descrevendo muito bem o incremento do número de átomos presentes na armadilha magnéto-óptica quando a luz de dessorção é acionada. Desse ajuste, a taxa de dessorção e o coeficiente de adsorção são estimados em 5x1017 átomos por segundo e 55 s-1. A união desse modelo com o proposto por Monroe et al. (1990), para o caso sem luz, descreve perfeitamente a curva experimental gerada quando o mecanismo para a obtenção da armadilha magnéto-óptica e a luz de dessorção são acionados simultaneamente. Além disso, uma previsão teórica para a taxa de dessorção, a taxa de carregamento da armadilha magnéto-óptica e o número máximo de átomos aprisionados em função da potência da luz de dessorção é mostrada graficamente.
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Erickson, Christopher Joseph. "Development of a Strontium-87 Ion Interferometer." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2750.
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I present the construction of a low-velocity intense source (LVIS) of laser-cooled neutral strontium using permanent ring magnets. The LVIS consists of a magneto-optical trap from which cold strontium is extracted in a well-collimated beam. I also present the development and implementation of a full suite of low-noise, high-bandwidth laser control electronics including a microcontroller unit. This microcontroller remotely controls and monitors the current driver, temperature controller, and PID lock circuit for each diode laser simultaneously. The current driver output is accurate to within 2 micro-amps and repeatable to with a few nano-amps. The noise spectral density of the current driver hits a floor of 10^(-10) amps per root Hz at ~50 Hz and has a modulation bandwidth of ~50 MHz. The PID lock-circuit includes a scan-balancing option that we have used to scan an AR coated laser diode ~30 GHz mode-hop free. I describe the construction of an 80 mW frequency doubled 461 nm laser system using PPKTP for cooling and trapping neutral strontium in the LVIS. The LVIS, the electronics systems, and the 461 nm laser system represent major milestones on the way to producing a matter-wave interferometer using Sr-87 ions. The interferometer is based on an optical Raman transition between the hyperfine ground states of the Sr-87 ion. The ions will be produced by exciting the strontium LVIS beam to an auto-ionizing state in the continuum. In the interferometer two half-pi pulses of light and one pi pulse will be delivered to the ions to split and recombine their wave functions. I present calculations of the predicted sensitivity and a discussion of the possible applications. I present a method for locking a 407.8 nm laser to the 5s doublet S J=1/2 to 5p doublet P J=3/2 strontium ion transition in a neutral vapor. I present calculations for the necessary vacuum levels for the experiment and describe the preparation and assembly of the vacuum apparatus. The major vacuum system consists of two connected elastomer sealed chambers: one at 10^(-7) Torr and the other at 10^(-10) Torr separated by a region of low conductance. I present a Sr vapor cell constructed from standard CF fittings that allows the strontium to be heated to ~730 C, which can also be run as a thermal beam. I present a method for protecting the viewports on small-form alkali-earth vapor cells using lead or indium foil during the evaporation of oxide layers. Finally, I report on the current status of the experiment as well as detail future work on the apparatus.
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Nascimento, Valter Aragão do. "Dinâmica de colisões entre átomos de Rydberg frios." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-13092007-113228/.
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Processos colisionais envolvendo transferência de energia têm sido intensivamente investigados em amostras de átomos de Rydberg frios nos últimos anos. Alguns grupos de pesquisa têm interpretado tais processos utilizando um modelo de muitos corpos; nosso grupo tem explicado tais processos, considerando a interação de dois corpos em um potencial de ultralongo alcance e o movimento sob a ação de um potencial. Nesta tese nós investigamos tais processos de colisão envolvendo átomos de Rydberg frios, produzidos em uma armadilha magneto-óptica. A investigação da evolução temporal de estados de Rydberg produzidos por colisões para diferentes densidades atômicas nos permite demonstrar que o processo binário é dominante. Além disso, mostramos que a radiação de corpo negro não pode ser desprezada nestes experimentos. Finalmente, sugerimos melhorias para um modelo semi-clássico de dinâmica colisional proposto por nosso grupo.Collisional processes involving energy transfer have been intensively investigated in samples of cold Rydberg atoms in the last years. Some research groups have interpreted such processes using a many body model; on the other hand our group has explained such processes considering a two body interaction in an ultralong range potential and the atomic motion under the influence of such potential. In this work, we have investigated such atomic collisions involving cold Rydberg atoms, produced in a magneto-optical trap. The time evolution study of the Rydberg states produced by collisions for different atomic densities has shown us that the binary process is dominant in such system. Beyond that, we have shown that the radiation of black body cannot be neglected in these experiments. Finally, we suggest improvements for the semi-classical collissional dynamic model proposed by our group.