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Construção de um detector tipo catodo quente para detecção de átomos neutros e aplicação no estudo de deflexão de feixes atômicos por luz; Construction of a hot-cathode like detector for detection of neutral atoms and its application in the study of the deflection of atomic beams by light

Oliveira, Henrique Barcellos de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/01/1991 PT
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Um detector de catodo quente é construído. As características de operação foram medidas e estabelecido o ponto ótimo de operação na detecção de átomos de sódio. Uma aplicação do detector desenvolvido foi feita com experimentos de deflexão de feixe atômico por luz. Os casos para deflexão por onda caminhante e onda estacionária foram investigados. A dependência com a dessintonia entre a freqüência do laser ω∫ e a freqüência da transição 3S1/2 (F=2, m=2) → 3P3/2 (F=3, m=3) do átomo de sódio foi analisada para todos os casos.; A hot wire detector has been constructed. The operational characteristics were measured and the optimum operational point was established in sodium atoms detection experiment. An application of the developed detector was made with atomic beams deflections by light. The cases for running wave and standing wave were also investigated. The detuning dependence between the laser frequency ω∫ and the transition frequency 3S1/2 (F=2, m=2) → 3P3/2 (F=3, m=3) of the sodium atom was analyzed for all cases.

Manipulação transversal de feixes atômicos para possível uso em litografia atômica; Transverse manipulation of atomic beams with potential use in atomic litography

Alves, Marcos Veríssimo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/10/1997 PT
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Desde o desenvolvimento de técnicas para controlar o movimento atômico usando a força de pressão de radiação, muitas aplicações tem sido sugeridas e implementadas. Entre estas, o aprisionamento atômico e o desenvolvimento de estruturas espaciais com átomos frios merece atenção especial devido à sua potencial aplicação em depósitos superficiais como litografia. Realizamos, neste trabalho, um estudo sobre feixes atômicos e sua desaceleração e compressão espacial. Realizamos também estudos numéricos sobre a formação de estruturas em anéis em feixes atômicos, verificando ser factível, e estudando também a compressão destas estruturas espaciais, com vistas a possíveis aplicações em nanolitografia atômica.; From the very beginning of the development of atomic motion control techniques using the radiation pressure force, a variety of applications have been suggested and implemented. Of all these, atomic trapping techniques and the development of spatial structures using cold atoms deserves special attention due to its potential application to surface deposition such as lithography. In the present work, we perform a study on atomic beams and their deceleration and spatial compression. We also perform numerical studies and present experimental observation of the realization of spatial ring structures in atomic beams...

Possibilidades de produção de feixes atômicos monoenergéticos; Prospects for producing monoenergetic atomic beams

Colussi, Valdir Carlos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/07/1992 PT
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Neste trabalho, apresentamos um estudo detalhado da técnica de desaceleração e aceleração de átomos pelo ajuste Zeeman, possibilitando a produção de um feixe atômico monoenergético. Usando esta técnica, realizamos estudos sobre efeito de bombeameto óptico e condições de seguimento adiabático dos átomos no campo magnético. Através do entendimento destes efeitos, pudemos propor modificações que permitirão a produção de um fluxo intenso de átomos monoenergéticos, que deverão permitir experimentos, com este tipo de feixe atômico, fora do sistema; We have carefully studied the Zeeman-tuned technique to decelerate and also accelerate sodium atoms atomic beam, creating ways of producing monoenergetic atomic beams. A systematic study of the optical pumping effects on these beams, as well as its adiabatic following conditions along the magnetic field were also investigated. A single laser beam, together with minor changes on the the magnetic field profile and on the optical setup, was used to decelerate and/or to accelerate atoms running outside of the Zeeman solenoid, simplifying and speeding up the experimental runs

Carregamento de armadilhas magneto-óticas a partir de feixes atômicos desacelerados para realização da condensação de Bose-Einstein; Magneto optical traps loaded from decelarated atomic beams for producing Bose-Einstein condensates

Miranda, Sérgio Gustavo de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/03/1999 PT
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Este trabalho teve como finalidade o desenvolvimento de uma técnica de carga para armadilhas magnéticas-óticas. Nosso objetivo com este desenvolvimento foi aumentar a eficiência do aprisionamento de modo a possibilitar sua utilização como etapa inicial na geração de condensados de Bose-Einstein. Com este intuito utilizamos feixes atômicos desacelerados em substituição a liberação de vapor na câmara da armadilha, desta forma eliminando as limitações no vácuo. O elemento distintivo de nossa técnica se baseou na utilização de um disco opaco. Este possuía a função de gerar uma sombra no laser responsável pela desaceleração dos átomos. Ao projetar esta sombra sobre a região de formação da armadilha evitamos os efeitos destrutivos do laser sobre a mesma. Desta maneira conseguimos aumentar consideravelmente o número de átomos aprisionados excepcionalmente em relação a carga a partir vapor, atingindo um número de 7.108 e densidade de 1010 átomos/cm3 numa situação otimizada; The goal was to learn and to develop efficient techniques to be used for quickly loading magneto optical traps. It may become usefull during the first steps towards producing Bose-Einstein condensates. A few different aproaches were attempted in order to avoid the loading from the surrounding thermal vapor. The key factor was the use of an opaque...

Mirror design for two-dimensional magneto-optic lenses and compressors

Milic, D; Hoogerland, Maarten; Baldwin, Kenneth; Buckman, Stephen
Fonte: Optical Society of America Publicador: Optical Society of America
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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Mirror design for two-dimensional magneto-optic lenses and compressors was analyzed. The mirror arrangement that enables large interaction lengths between atomic beams and laser fields by use of a small amount of laser power was presented. The application

Nonlocal Stabilization of Nonlinear Beams in a Self-focusing Atomic Vapor

Skupin, Stephan; Saffman, Mark; Krolikowski, Wieslaw
Fonte: American Physical Society Publicador: American Physical Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.73444%
We show that ballistic transport of optically excited atoms in an atomic vapor provides a nonlocal nonlinearity which stabilizes the propagation of vortex beams and higher order modes in the presence of a self-focusing nonlinearity. Numerical experiments

Magnetic hexapole lens focusing of a metastable helium atomic beam for UV-free lithography

Chaustowski, Rene; Leung, V.; Baldwin, Kenneth
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
57.547856%
Sources of rare gas atoms in excited metastable states have been used to expose photoresist-coated substrates to demonstrate atom lithography. These thermal atomic beams are usually created by discharge sources that also produce copious amounts of UV radi

Multibeam atom laser: Coherent atom beam splitting from a single far-detuned laser

Dugue, J; Dennis, Graham; Jeppesen, M; Johnsson, Mattias; Figl, Cristina; Robins, Nicholas; Close, John
Fonte: American Physical Society Publicador: American Physical Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.64574%
We report the experimental realization of a multibeam atom laser. A single continuous atom laser is outcoupled from a Bose-Einstein condensate via an optical Raman transition. The atom laser is subsequently split into up to five atomic beams with slightly

Four-Color Stimulated Optical Forces for Atomic and Molecular Slowing

Galica, S. E.; Aldridge, L.; Eyler, E. E.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.459155%
Stimulated optical forces offer a simple and efficient method for providing optical forces far in excess of the saturated radiative force. The bichromatic force, using a counterpropagating pair of two-color beams, has so far been the most effective of these stimulated forces for deflecting and slowing atomic beams. We have numerically studied the evolution of a two-level system under several different bichromatic and polychromatic light fields, while retaining the overall geometry of the bichromatic force. New insights are gained by studying the time-dependent trajectory of the Bloch vector, including a better understanding of the remarkable robustness of bi- and polychromatic forces with imbalanced beam intensities. We show that a four-color polychromatic force exhibits great promise. By adding new frequency components at the third harmonic of the original bichromatic detuning, the force is increased by nearly 50% and its velocity range is extended by a factor of three, while the required laser power is increased by only 33%. The excited-state fraction, crucial to possible application to molecules, is reduced from 41% to 24%. We also discuss some important differences between polychromatic forces and pulse trains from a high-repetition-rate laser.; Comment: 9 pages...

Generation of neutral atomic beams utilizing photodetachment by high power diode laser stacks

O'Connor, A. P.; Bruhns, H.; Grussie, F.; Koenning, T. P.; Miller, K. A.; de Ruette, N.; Stützel, J.; Savin, D. W.; Urbain, X.; Kreckel, H.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/09/2015
Relevância na Pesquisa
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We demonstrate the use of high power diode laser stacks to photodetach fast hydrogen and carbon anions and produce ground term neutral atomic beams. We achieve photodetachment efficiencies of $\sim$7.4\% for H$^-$ at a beam energy of 10\,keV and $\sim$3.7\% for C$^-$ at 28\,keV. The diode laser systems used here operate at 975\,nm and 808\,nm, respectively, and provide high continuous power levels of up to 2\,kW, without the need of additional enhancements like optical cavities. The alignment of the beams is straightforward and operation at constant power levels is very stable, while maintenance is minimal. We present a dedicated photodetachment setup that is suitable to efficiently neutralize the majority of stable negative ions in the periodic table.

Two-dimensional atomic lithography by sub-micron focusing of atomic beams

Williams, W.; Saffman, M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 02/06/2005
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We analyze a method for serial writing of arbitrary two-dimensional patterns using optical focusing of a collimated atomic beam. A spatial light modulator is used in a side illumination geometry to create a localized optical spot with secondary maxima that are well separated from the central peak. Numerical simulation of a lithography experiment using a magneto-optical trap as a source of cold Cs atoms, collimation and cooling in a magnetic guide, and optical focusing predicts full width at half maximum pixel sizes of 110 x 110 nm and writing times of about $20 \rm ms$ per pixel.; Comment: 12 figures

Nanofabrication by magnetic focusing of supersonic beams

Clark, Robert J.; Mazur, Thomas R.; Libson, Adam; Raizen, Mark G.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.459155%
We present a new method for nanoscale atom lithography. We propose the use of a supersonic atomic beam, which provides an extremely high-brightness and cold source of fast atoms. The atoms are to be focused onto a substrate using a thin magnetic film, into which apertures with widths on the order of 100 nm have been etched. Focused spot sizes near or below 10 nm, with focal lengths on the order of 10 microns, are predicted. This scheme is applicable both to precision patterning of surfaces with metastable atomic beams and to direct deposition of material.; Comment: 4 pages, 3 figures

Nonlinear Variation of Light-Pressure-Induced Multilevel Atomic Line Shifts with Vapor Pressure in Helium Spectroscopy

Zelevinsky, T.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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This paper has been temporarily withdrawn. Highly nonlinear dependences of 4He 2^3S - 2^3P lines on pressure were observed in vapor cell saturation spectroscopy. Line shifts agree with those expected from light-pressure-induced perturbation of atomic velocity distribution. In the lin-perp-lin pump and probe polarization configuration, multilevel atomic structure must be taken into account. For a two-level atom, the shift magnitude is determined by the collisional time constant, but when the system has dark states there is an additional time constant due to optical pumping. The collisional and optical time constants compete, and become equal at a certain pressure p_0. Saturation signal vanishes at p_0 whereas signal due to light pressure remains. This leads to a dependence of line centers on pressure that exhibits apparently singular behavior at p_0. The 2S - 2P(J=1) line shift reaches the natural half width. Vapor cells may be more suitable for investigation of this effect than atomic beams since the shifts vanish at sufficiently high pressures. Two ways of controlling the shifts for the helium 2P fine structure measurement are discussed.; Comment: This paper has been temporarily withdrawn

Generation of macroscopic pair-correlated atomic beams by four-wave mixing in Bose-Einstein condensates

Vogels, J. M.; Xu, K.; Ketterle, W.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 13/03/2002
Relevância na Pesquisa
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By colliding two Bose-Einstein condensates we have observed strong bosonic stimulation of the elastic scattering process. When a weak input beam was applied as a seed, it was amplified by a factor of 20. This large gain atomic four-wave mixing resulted in the generation of two macroscopically occupied pair-correlated atomic beams.; Comment: Please take eps files for best details in figures

Detecting the Harmonic Vibrations of Micro Amplitudes and Low Frequencies with Atomic Mach-Zehnder Interferometer

Huang, Yong-Yi
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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We study the effects of atomic beams harmonic vibrations of micro amplitudes and low frequencies on the mean atomic numbers of the detectors in atomic Mach-Zehnder interferometer, where the two atomic beams are in the same wave surface and have the same phases. We propose a vibrant factor F to quantitatively describe the effects of atomic beams vibrations. It shows that: (i)the vibrant factor F depends on the relative vibrant displacements and the initial phases rather than the absolute amplitudes, (ii)the factor F increases with the increase of the initial phases, and (iii)the frequencies can be derived from equal time interval measurement of the mean atomic numbers. These results imply that it is possible to detect the vibrations of micro amplitudes and low frequencies by measuring the variations of mean atomic numbers.; Comment: 10 pages, 2 figures, to appear in General Relativity and Gravitation

Bessel beams of two-level atoms driven by a linearly polarized laser field

Hayrapetyan, Armen G.; Matula, Oliver; Surzhykov, Andrey; Fritzsche, Stephan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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We study Bessel beams of two-level atoms that are driven by a linearly polarized laser field. Starting from the Schroedinger equation, we determine the states of two-level atoms in a plane-wave field respecting propagation directions both of the atom and the field. For such laser-driven two-level atoms, we construct Bessel beams beyond the typical paraxial approximation. We show that the probability density of these atomic beams obtains a non-trivial, Bessel-squared-type behavior and can be tuned under the special choice of the atom and laser parameters, such as the nuclear charge, atom velocity, laser frequency, and propagation geometry of the atom and laser beams. Moreover, we spatially and temporally characterize the beam of hydrogen and selected (neutral) alkali-metal atoms that carry non-zero orbital angular momentum (OAM). The proposed spatiotemporal Bessel states (i) are able to describe, in principle, twisted states of any two-level system which is driven by the radiation field and (ii) have potential applications in atomic, nuclear processes and quantum communication.; Comment: 13 pages, 5 figures, appeared as a EPJD highlight on Thursday, 01 August 2013 http://www.epj.org/index.php?option=com_content&view=article&id=684%3Aepjd-highlight-novel-beams-made-of-twisted-atoms&catid=112%3Aepj-d&Itemid=466&lang=en

Velocity distribution measurements in atomic beams generated using laser induced back-ablation

Denning, A.; Booth, A.; Lee, S.; Ammonson, M.; Bergeson, S. D.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 28/10/2008
Relevância na Pesquisa
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We present measurements of the velocity distribution of calcium atoms in an atomic beam generated using a dual-stage laser back-ablation apparatus. Distributions are measured using a velocity selective Doppler time-of-flight technique. They are Boltzmann-like with rms velocities corresponding to temperatures above the melting point for calcium. Contrary to a recent report in the literature, this method does not generate a sub-thermal atomic beam.; Comment: 4 pages, 3 figures

Squeezing and entanglement of atomic beams

Duan, L. -M.; Sørensen, A.; Cirac, J. I.; Zoller, P.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/07/2000
Relevância na Pesquisa
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We propose and analyze a scheme for generating entangled atomic beams out of a Bose-Einstein condensate using spin-exchanging collisions. In particular, we show how to create both atomic squeezed states and entangled states of pairs of atoms.; Comment: 4 pages, 2 figures

Quantum correlated twin atomic beams via photo-dissociation of a molecular Bose-Einstein condensate

Kheruntsyan, K. V.; Drummond, P. D.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.501606%
We study the process of photo-dissociation of a molecular Bose-Einstein condensate as a potential source of strongly correlated twin atomic beams. We show that the two beams can possess nearly perfect quantum squeezing in their relative numbers.; Comment: Corrected LaTeX file layout

Geometric optics with atomic beams scattered by a detuned standing laser wave

Prants, S. V.; Vitkovsky, V. O.; Konkov, L. E.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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We report on theoretical and numerical study of propagation of atomic beams crossing a detuned standing-wave laser beam in the geometric optics limit. The interplay between external and internal atomic degrees of freedom is used to manipulate the atomic motion along the optical axis by light. By adjusting the atom-laser detuning, we demonstrate how to focus, split and scatter atomic beams in a real experiment. The novel effect of chaotic scattering of atoms at a regular near-resonant standing wave is found numerically and explained qualitatively. Some applications of the effects found are discussed.