xvi, 119 p. ; ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / This dissertation describes the development of an apparatus that can accommodate many atom-optics experiments, as well as an experimental demonstration of an optical one-way barrier for neutral atoms. The first part of this dissertation describes in detail the design and implementation of our apparatus. The experiment setup consists of optical systems, vacuum systems, imaging systems, and the related electronics. It is designed to be versatile enough for many cold-atom experiments, including the demonstration of an optical one-way barrier for neutral atoms, quantum measurement on the single-atom level, and the study of quantum chaos using Bose-Einstein condensates. The second part of this thesis presents the experimental study of an optical one-way barrier for neutral atoms. We demonstrated an asymmetric optical potential barrier for ultracold 87 Rb atoms. The atoms are confined in a far-detuned dipole trap consisting of a single focused Gaussian beam from a fiber laser. The optical one-way barrier consists of two focused laser beams oriented nearly normal to the dipole-trap axis and tuned near the 87 Rb D 2 transition. The first beam (main barrier beam) is tuned to work as either a potential well or barrier, depending on the state of the incident atoms. The second beam (repumping barrier beam) pumps the atoms to the barrier state on the reflecting side. We investigated the transmission and reflection dynamics of the atoms in the presence of the one-way barrier, and we verified its capability for increasing the phase-space density of a sample of neutral atoms using the one-way barrier. Our experiment is a realization of Maxwell's demon and has important implications for cooling atoms and molecules not susceptible to the standard laser-cooling techniques. / Adviser: Daniel A. Steck

Realizamos neste trabalho a construção de um Oscilador Paramétrico Ótico triplamente ressonante bombeado por um laser de Titânio Safira sintonizável na faixa entre 730 nm e 800 nm com potencial de extensão. Os feixes emitidos possuem comprimento de onda em torno de 1560 nm que estão na janela de transmissão das fibras óticas, com potência de saída máxima em torno de 420 mW e um limiar de oscilação mínimo de 53(3) mW quando bombeado por 780.126(0.03) nm. Para os feixes gêmeos a finesse da cavidade vale F=155 e as perdas intracavidade 0.05(0.1)%, permitindo, em tese, uma compressão de ruído próxima a 97(6)%. Esse OPO foi construído com o propósito de que o utilizemos como fonte geradora de estados triplamente emaranhados em um sistema de armazenamento e transferência de informação quântica quando em interação com um sistema atômico de rubídio. Medimos a potência de limiar e a eficiência de conversão para cada comprimento de onda do feixe de bombeio utilizado para caracterizar o sistema. / At the present work we conducted the construction of a triply resonant Optical Parametric Oscillator pumped by a Titanium-Sapphire laser, which is tunable between 730 nm to 800 nm. The emitted beams have wavelength around 1560 nm, in the optical fibers transmission window, maximum output of 420 mW and minimum oscillation threshold of 53(3) mW. For the twin beams, the cavity finesse is F=155 mW and the intracavity losses are 0.05(0.10)%, allowing, in principle, a noise compression close to 97(5)%. The present OPO was built having the purpose of being used as source of triply entangled states in a system for quantum information storage and transfer, while interacting with an atomic rubidium system. We measured the power threshold and conversion efficiency for each pump beam wavelength that we used to characterize the system.

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.

We have developed a technique to produce, manipulate and trap Rb2 molecules with a single optical beam. This beam is generated by a high-power fiber amplifier (50 W of total output power) in the 1060 to 1070 nm range, which is seeded by two light sources: a sharp-band laser and a broadband superluminescent diode. The laser source is tuned to produce Rb2 molecules from an ultracold 85Rb sample via photoassociation. The broadband spectrum vibrationally cool the molecules by optical pumping. This source is spectrally shaped in order to populate the molecules at the fundamental vibrational state ν = 0. The molecular sample is probed by two-photon ionization, promoted by a pulsed dye laser in the 475 to 480 nm range. By scanning the photoassociation laser frequency, we have obtained a photoassociation spectrum of the ν\' = 138 state of the 0+u potential, confirming previous observations. We have also obtained two vibrational spectra of the molecules by varying the ionization laser frequency, in the presence and absence of the broadband source. The comparison between the two spectra, along with ab-initio data, provides evidences that the molecules are optically pumped to the fundamental vibrational state. / Desenvolvemos uma técnica para produzir, manipular e aprisional moléculas de Rb2 com um único feixe óptico. Esse feixe é gerado por um amplificador de alta potência (50 W de potência total de saída) na faixa de 1060 a 1070 nm, que é alimentado por duas fontes de luz: um laser banda estreita e um diodo superluminescente banda larga. O laser é sintonizado para produzir moléculas de Rb2 a partir de uma amostra ultrafria de 85Rb via fotoassociação. O espectro banda larga resfria vibracionalmente as moléculas, por bombeamento óptico. Essa fonte de luz tem seu espectro formatado de modo a deixar as moléculas em seu estado vibracional fundamental ν = 0. A amostra molecular é testada por ionização de dois fótons, promovida por um laser de diodo pulsado na faixa de 475 a 480 nm. Variando a frequência do laser de fotoassociação, obtivemos um espectro de fotoassociação do estado ν\' = 138 do potencial 0+u, confirmando observações anteriores. Obtivemos também dois espectros vibracionais das moléculas variando a frequência do laser de ionização, com e sem a fonte banda larga. Uma comparação entre os dois espectros, junto de dados ab-initio, fornece evidências de que as moléculas são opticamente bombeadas para o estado vibracional fundamental.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2016-12-07T12:55:23Z No. of bitstreams: 1 Geimson Ayrcton dos Santos.pdf: 2542495 bytes, checksum: c8980a31079b32fd9ab6810390ce0a4d (MD5) / Made available in DSpace on 2016-12-07T12:55:23Z (GMT). No. of bitstreams: 1 Geimson Ayrcton dos Santos.pdf: 2542495 bytes, checksum: c8980a31079b32fd9ab6810390ce0a4d (MD5) Previous issue date: 2016-08-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work we study a resonant fluorescence signal generated by two-photon absorption in rubidium vapor, when the atomic system interacts with a continuous wave laser from a diode laser beam and one ultrashort pulse train from a femtosecond Ti:sapphire laser, in the ladder transition 5S1/2 -> 5P3/2 -> 5D5/2. The atoms contained in a closed and heated cells interact with the pair of laser beams in a co-propagating con guration. The laser beams have wavelengths of about 780 nm and linear and parallel polarization. We analyze the fluorescence signal detected forward, in the same direction of the incidence laser beams, as well as in the direction perpendicular to lasers ( fluorescence at 90º). We analyze the fluorescence signal at 421 nm generated by the spontaneous decay of the excited state 6P3/2 to the ground state 5S1/2 of rubidium, as a function of the many parameters of the system, such as: the signal polarization with respect to the polarization of the laser beams, the frequency and the intensity of the diode laser, and the atomic density of the sample. We observed saturation e ects on the fluorescence detected signal varying the intensity of the laser diode and the atomic density. E ects of an optical pumping from the diode laser beam on the fluorescence signal were observed and explained with a simple theoretical model. / Neste trabalho estudamos um sinal de fluorescência ressonante por dois fótons em vapor de rubídio ao interagir com um feixe de laser de diodo e com um laser de Ti:sa ra de femtossegundos na transição em cascata 5S1/2 -> 5P3/2 -> 5D5/2. Os átomos contidos em uma célula fechada e aquecida interagem com os feixes de lasers na configuração copropagante, tendo comprimentos de onda em torno de 780 nm e polarizações lineares e paralelas entre si. Analisamos o sinal de fluorescência detectado para frente, na direção de incidência dos lasers, bem como na direção perpendicular aos lasers (fluorescência a 90º ). Analisamos o sinal de fluorescência no comprimento de onda 421 nm devido ao decaimento espontâneo do estado excitado 6P3/2 para o estado fundamental 5S1/2, em função de vários parâmetros do sistema, como a polarização do sinal em relação a polarização dos lasers, em função da frequência de varredura do laser de diodo e em função da densidade atômica da amostra. Observamos efeitos de saturação no sinal de fluorescência variando-se a intensidade do laser de diodo e a densidade atômica. Efeitos de bombeio óptico do laser de diodo no sinal de fluorescência detectado também foram observados e explicados com um modelo teórico simples.

Dual-comb spectroscopy (DCS) has widespread applications. It has become a more prominent spectroscopic tool because it has broad spectral coverage with high frequency resolution. We demonstrate the broadband and high resolution of DCS to probe transient events, showing the rst use of DCS of laser-induced plasmas (LIPs). Our measurements span absorption features 7 THz wide, simultaneously detecting Rb D2, K D1 and D2 absorption lines with the ability to resolve the isotope ratios in the Rb D2 line. This technique is more broadband and faster than tunable laser absorption spectroscopy because it eliminates the requirement to scan across transitions. Additionally, DCS makes higher resolution measurements than laser-induced break- down spectroscopy. Our ultimate goal is to use DCS as a technique to ascertain the chemical composition of unknown samples. Our rst demonstration of this technique illustrates that DCS makes broadband, high-resolution measurements with the ability to measure isotope ratios, which is necessary for determining sample composition.

The aim of master's thesis is separation rubidium from cement bypass dust by columns based od hexacyanoferric and resins

No description available.

Light-matter interactions are fundamentally based on the quantum mechanical principles that govern photons, electrons and other fundamental particles. One very interesting phenomenon within all of light-matter interactions is Electromagnetically Induced Transparency(EIT). This phenomenon causes an otherwise absorbing atomic transition to stop absorbing through quantum mechanical interference of probability wave functions. Corresponding to that change in absorption, will be a sudden, large change in the index of refraction. This change in the index of refraction leads to another phenomenon in which the group velocity of light can be slowed down dramatically. In the past, many researchers have been able to achieve both EIT and slow light in bulk atomic vapor cells. In an attempt to miniaturize this process and we have been using a platform of Anti Resonant Reflecting Optical Waveguides (ARROW) devices to both guide light and contain the interacting matter. However, the platform creates a whole new set of challenges when integrating rubidium vapor into the hollow waveguides as rubidium is highly reactive and it is difficult to maintain an inert atmosphere for the rubidium vapor. A variety of sealing methods were attempted and their appropriateness and effectiveness was analyzed. Among these sealing methods were PMMA, Crystal Wax, Active Solder, Epoxy, and Indium Solder. PMMA, Crystal Wax and Active Solder each had major faults in one or more of the sealing requirements. We have used a high temperature epoxy with relative success to contain the rubidium vapor. However, the epoxy degrades very quickly at the high temperatures required for EIT testing. Indium solder is the most recent application method. It has high potential although we have yet to fully test its effectiveness. We were able to successfully demonstrate the first EIT and slow light on a chip with our ARROW atomic vapor cell system. In the slow light experiment, we were able to slow light down to 2.5x105m/s. The group velocity of light decreased from the standard 3x108m/s by a factor of 1200. We believe we can achieve even lower group velocities using this same platform through further experimentation.

No abstract provided. / Thesis / Doctor of Philosophy (PhD) / Scope and contents: The atomic vibrations in rubidium have been studied by the method of slow neutron spectrometry. The results have been analysed to yield atomic force constants which are used to compute the phonon frequency distribution. An interesting effect in the [00ζ]L branch has been examined, and an explanation of the observations is offered. Anharmonic calculations of frequency shifts and widths are presented, as well as a calculation of the anharmonic heat capacity. The third and fourth derivatives of the real space interatomic potential, which are required for these computations, are estimated in various ways. A determination of the lattice spacing of rubidium by neutron diffraction is described.