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1
Paskauskas, Rytis. "Chaotic Scattering in Rydberg Atoms, Trapping in Molecules." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19809.
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We investigate chaotic ionization of highly excited hydrogen atom in crossed electric and magnetic fields (Rydberg atom) and intra-molecular relaxation in planar carbonyl sulfide (OCS) molecule. The underlying theoretical framework of our studies is dynamical systems theory and periodic orbit theory. These theories offer formulae to compute expectation values of observables in chaotic systems with best accuracy available in given circumstances, however they require to have a good control and reliable numerical tools to compute unstable periodic orbits. We have developed such methods of computation and partitioning of the phase space of hydrogen atom in crossed at right angles electric and magnetic fields, represented by a two degree of freedom (dof) Hamiltonian system. We discuss extensions to a 3-dof setting by developing the methodology to compute unstable invariant tori, and applying it to the planar OCS, represented by a 3-dof Hamiltonian. We find such tori important in explaining anomalous relaxation rates in chemical reactions. Their potential application in Transition State Theory is discussed.
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Ganeshalingam, Sashikesh. "Charge transfer of Rydberg hydrogen molecules and atoms at doped silicon surfaces." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:9f1f6bb6-47a0-47f6-ad55-52f416d08815.
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The work of this thesis focuses on the interaction of high Rydberg states of hydrogen molecules and atoms with various doped Si semiconductor surfaces with the results compared with those obtained with an atomically flat gold surface. The major part of the thesis was carried out using para-H₂ molecular Rydberg states with principal quantum number n = 17 - 21 and core rotational quantum number N⁺ = 2. Subsequently, this study was continued using H atomic Rydberg states with principal quantum number n = 29 - 34. The high Rydberg states have been produced using two-step laser excitation. For close Rydberg surface separation (< 6 n² a.u.), the Rydberg states may be ionized due to an attractive surface potential experienced by the Rydberg electron, and the remaining ion core may be detected by applying an external electric field. An efficient ion detectability method is introduced to compare the many surface ionization profiles quantitatively. The p-type doped Si surfaces enhance the detected ion-signal more than the n-type doped Si surfaces due to the presence of widely distributed positive dopant charge fields in the p-type doped Si surfaces. As the dopant density increases, the area sampled by the resultant ions becomes effectively more neutral, and the decay rate of the potential from the surface dopant charge with distance from the surface becomes more rapid. Therefore, the minimum ionization distance is also reduced with increasing dopant density. It is found that the detected ion-signal decreases with increasing dopant density of both p- and n- type doped Si surfaces. The higher-n Rydberg states have shown higher ion detectability than that of lower-n Rydberg states and this variation also becomes smaller when increasing the dopant density. Experiments involving H2 Rydberg molecules incident on various doped Si surfaces in the presence of a Stark field at the point of excitation are also presented here. The surface ionization profiles produced via both electron and ion detection schemes are measured by changing the Stark polarization. Positive surface dopant charges oppose production of backscattered electrons and negative surface dopant charges enhance the electron-signal. For the electron detection scheme, lightly doped n-type Si surfaces show higher detectability but in the case of p-type Si surfaces the more heavily doped Si surfaces give a higher detected signal. This different behaviour of the detected ion or electron signal implies a different production mechanism. Theoretical trajectory simulations were also carried out based on a new 2D surface potential model. The results qualitatively agree with the experimental results and explain the changes of the surface ionization profiles between the various dopant types and dopant densities of the Si surfaces.
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Butscher, Björn [Verfasser], and Tilman [Akademischer Betreuer] Pfau. "A Rydberg interferometer : from coherent formation of ultralong-range Rydberg molecules to state tomography of Rydberg atoms / Björn Butscher. Betreuer: Tilman Pfau." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2011. http://d-nb.info/1014277388/34.
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Liu, Ivan Chen-Hsiu. "Ultracold Rydberg Atoms in Structured and Disordered Environments." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1231945394343-32656.
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The properties of a Rydberg atom immersed in an ultracold environment were investigated. Two scenarios were considered, one of which involves the neighbouring ground-state atoms arranged in a spatially structured configuration, while the other involves them distributed randomly in space. To calculate the influence of the multiple ground-state atoms on the Rydberg atom, Fermi-pseudopotential was used, which simplified greatly the numerical effort. In many cases, the few-body interaction can be written down analytically which reveals the symmetry properties of the system. In the structured case, we report the first prediction of the formation of ``Rydberg Borromean trimers''. The few-body interactions and the dynamics of the linear A-B-A trimer, where A is the ground-state atom and B is the Rydberg atom, were investigated in the framework of normal mode analysis. This exotic ultralong-range triatomic bound state exists despite that the Rydberg-ground-state interaction is repulsive. Their lifetimes were estimated using both quantum scattering calculations and semi-classical approximations which are found to be typically sub-microseconds. In the disordered case, the Rydberg-excitation spectra of a frozen-gas were simulated, where the nuclear degrees of freedom can be ignored. The systematic change of the spectral shape with respect to the density of the gas and the excitation of the Rydberg atom were found and studied. Some parts of the spectral shape can be described by simple scaling laws with exponents given by the basic properties of the atomic species such as the polarizability and the zero-energy electron-atom scattering length.
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Liu, Ivan Chen-Hsiu. "Ultracold Rydberg Atoms in Structured and Disordered Environments." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23624.
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The properties of a Rydberg atom immersed in an ultracold environment were investigated. Two scenarios were considered, one of which involves the neighbouring ground-state atoms arranged in a spatially structured configuration, while the other involves them distributed randomly in space. To calculate the influence of the multiple ground-state atoms on the Rydberg atom, Fermi-pseudopotential was used, which simplified greatly the numerical effort. In many cases, the few-body interaction can be written down analytically which reveals the symmetry properties of the system. In the structured case, we report the first prediction of the formation of ``Rydberg Borromean trimers''. The few-body interactions and the dynamics of the linear A-B-A trimer, where A is the ground-state atom and B is the Rydberg atom, were investigated in the framework of normal mode analysis. This exotic ultralong-range triatomic bound state exists despite that the Rydberg-ground-state interaction is repulsive. Their lifetimes were estimated using both quantum scattering calculations and semi-classical approximations which are found to be typically sub-microseconds. In the disordered case, the Rydberg-excitation spectra of a frozen-gas were simulated, where the nuclear degrees of freedom can be ignored. The systematic change of the spectral shape with respect to the density of the gas and the excitation of the Rydberg atom were found and studied. Some parts of the spectral shape can be described by simple scaling laws with exponents given by the basic properties of the atomic species such as the polarizability and the zero-energy electron-atom scattering length.
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Waterland, Robert Leonard. "Rydberg atoms in parallel electric and magnetic fields." W&M ScholarWorks, 1986. https://scholarworks.wm.edu/etd/1539623768.
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I have calculated the energy spectrum of a highly excited atom which lies in parallel, static electric and magnetic fields. In parallel fields the Coulomb quantum numbers n and m are still "good" quantum numbers but 1 is not: the calculation is for n = 30, m = 1 atoms.;The eigenvalues were obtained by semi-classical quantisation of first-order classical perturbation theory and have been calculated for a large range of electric and magnetic field strengths. The results are in good agreement with those found from first-order degenerate quantum perturbation theory.;The semi-classical analysis provides a correlation diagram connecting the Stark effect states to those of the diamagnetic effect.
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Schmid, Thomas [Verfasser]. "Rydberg Molecules for Ultracold Ion-Atom Scattering / Thomas Schmid." München : Verlag Dr. Hut, 2019. http://d-nb.info/1196415536/34.
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Sharkey, Keeper Layne. "Very Accurate Quantum Mechanical Non-Relativistic Spectra Calculations of Small Atoms & Molecules Employing All-Particle Explicitly Correlated Gaussian Basis Functions." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/560835.
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Due to the fast increasing capabilities of modern computers it is now feasible to calculate spectra of small atom and molecules with the greater level of accuracy than high-resolution measurements. The mathematical algorithms developed and implemented on high performance supercomputers for the quantum mechanical calculations are directly derived from the first principles of quantum mechanics. The codes developed are primarily used to verify, refine, and predict the energies associated within a given system and given angular momentum state of interest. The Hamiltonian operator used to determine the total energy in the approach presented is called the internal Hamiltonian and is obtained by rigorously separating out the center-of-mass motion (or the elimination of translational motion) from the laboratory-frame Hamiltonian. The methods utilized in the articles presented in this dissertation do not include relativistic corrections and quantum electrodynamic effects, nor do these articles assume the Born-Oppenheimer (BO) approximation with the exception of one publication. There is one major review article included herein which describes the major differences between the non-BO method and the BO approximation using explicitly correlated Gaussian (ECG) basis functions. The physical systems studied in this dissertation are the atomic elements with Z < 7 (although the discussion is not limited to these) and diatomic molecules such as H₂⁺ and H₂ including nuclear isotopic substitution studies with deuterium and tritium, as well as electronic substitutions with the muon particle. Preliminary testing for triatomic molecular functionals using a model potential is also included in this dissertation. It has been concluded that using all-particle ECGs with including the addition of nonzero angular momentum functions to describe nonzero angular momentum states is sufficient in determining the energies of these states for both the atomic and molecular case.
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Qadiri, Rafay Hasan. "H (Rydberg) atom photofragment translational spectroscopy of unsaturated hydride molecules." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411071.
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Nipper, Johannes Maximilian [Verfasser], and Tilman [Akademischer Betreuer] Pfau. "Interacting Rydberg atoms : coherent control at Förster resonances and polar homonuclear molecules / Johannes Maximilian Nipper. Betreuer: Tilman Pfau." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2012. http://d-nb.info/1028799993/34.
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Comparat, Daniel. "EXPERIENCES AVEC DES ATOMES DE RYDBERG ET DES MOLECULES ULTRA-FROIDS." Habilitation à diriger des recherches, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00343528.
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Cabral, Jader de Souza. "Ressonâncias Moleculares em átomos de Rydberg frios." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-19032009-160506/.
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O entendimento das interações de ultralongo alcance envolvendo átomos de Ryberg frios é o ponto principal para o uso deste sistema em computação quântica. Neste trabalho estudamos tais interações envolvendo estados nD+nD em um novo aparato experimental, o qual permite o controle de campo elétrico de uma forma mais eficiente. Mais especificamente estudamos o processo colisional $nD + nD$ $ightarrow$ $(n+2)P + (n-2)F$ na presença de campo elétrico estático fixo. Este processo é importante porque pode levar a decoerência da amostra. Os resultados obtidos indicam a existência de uma ressonância molecular que é sensível ao efeito Stark. Além disso, investigamos se o movimento atômico é importante para popular tais estados. Por fim, proporemos novos experimentos que podem ser úteis para controlar e suprimir tais processos colisionais e assim permitir avanços na área de computação quântica com tais sistemas.<br>The understanding of ultralong-range interaction involving cold Rydberg atoms is the main step for use this system in quantum computation. In this work, we have studied interaction involving $nD$ states in a new experimental setup, which allows us to control the electric field in a more efficient way. More specifically, we have studied the collision process $nD + nD ightarrow (n+2)P + (n-2)F$ in the presence of a static electric field. This process is important because it can lead to a decoherence of the sample. The observed results show the existence of a molecular resonance which is dependent of Stark effect. Moreover, the atomic motion is perhaps also important to populate such states. Finally, we propose new experiments that can be useful to control and to suppress theses colisional processes and in this way allows us to move on in quantum computing area with such systems.
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Kondo, Jorge Douglas Massayuki. "Estudo de colisões entre átomos de Rydberg ultrafrios em amostras atômicas aprisionadas numa armadilha óptica de dipolo." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-03022015-171234/.
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Neste trabalho, estudamos colisões entre átomos de Rydberg ultrafrios em uma amostra atômica de alta densidade aprisionada em uma armadilha óptica de dipolo (AOD) tipo QUEST (Quasi Electrostatic Trap). Nossos objetivos incluíam testar a manifestação de fenômenos de muitos corpos bem como estudar efeitos de anisotropia nos processos colisionais envolvendo dois corpos. Para isso, escolhemos o processo colisional descrito por 5/2+5/2(+2)3/2+(2)7/2 no intervalo de 37 ≤ ≤47. O processo foi estudado na ausência e presença de campo elétrico estático, originando as ressonâncias Förster. Os resultados mostram que mesmo em alta densidade atômica o processo de dois corpos domina a interação, apesar da clara manifestação do bloqueio dipolar. Após modificações na montagem experimental, estudamos um dos picos da ressonância Förster 375/2+375/2393/2+357/2 em função da direção e amplitude em relação ao eixo longitudinal da AOD. Discutimos os resultados e os desafios futuros do experimento.<br>In this paper, we study collisions between ultracold Rydberg atoms in a high density atomic sample trapped in an optical dipole trap (ODT), type QUEST (Quasi Electrostatic Trap). Our goals included testing the manifestation of many-body phenomena and to study anisotropy effects in collisional processes involving two Rydberg atoms. In order to do this, we have chosen the collision process described by 5/2+5/2(+2)3/2+(2)7/2 in the range of 37 ≤ ≤47. The process was studied in the presence and absence of a dc static electric field, also known as Förster resonances. The results show that even at high atomic density, two-body interaction dominates de process, despite the clear manifestation of Rydberg blockade. After several improvements in our experimental setup, we have studied also a Förster resonance peak 375/2+375/2393/2+357/2 as a function of the magnitude of the dc static electric field as well as the angle between this field and the longitudinal axis of the ODT. We discuss the results and future challenges of the experiment.
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Kondo, Jorge Douglas Massayuki. "Ressonâncias moleculares em estados nP de átomos de Rydberg frios." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-18112010-145903/.
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Neste trabalho estudamos a interação entre átomos de Rydberg no estado nP e sua dependência com o campo elétrico dc. Estes estados apresentam ressonâncias Föster para um número quântico principal n menor que 37. Nestes processos de ressonância um par atômico no estado nP muda para um par nS+(n+1)S. Realizamos dois experimentos de evolução temporal para 32≤n≤36. No primeiro investigamos a dependência da taxa de transferência de população NnS em função do número quântico principal n. E no segundo estudamos a transferência de população para um estado fixo de n=33 em função do campo elétrico. Além disso, estudamos a dependência da população no estado 33S em função da densidade de átomos de Rydberg no estado 33P. Estes resultados nos permitem observar duas contribuições distintas, uma linear relacionada a radiação de corpo negro e uma quadrática ligada a interação de dois corpos. Estes resultados confirmam o modelo de taxa para o efeito da radiação de corpo negro.<br>In this work we studied the role of Rydberg atoms interactions in the nP state and the dc electric field dependency of this process. The nP state shows Föster resonances for principal quantum number less than 37. In this resonance process, an atomic pair in nP state changes to a pair nS+(n+1)S. We have performed two time evolution experiments for 32≤n≤36. In the first one we have investigated the NnS population transfer rate for a variable principal quantum number n. In the second we have study the population transfer for a fixed n=33, by varying an electric field. Moreover, we observed the density dependency of the population in the 33S state by varying the nP state atomic density. The results allow us to observe two distinct contributions, a linear contribution related with the black body radiation and a quadratic one connected with two body process. The results agree well with the rate model used to treat the black body radiation.
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Balaraman, Gouthaman S. "Theoretical study of atomic processes and dynamics in ultracold plasmas." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26522.
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Thesis (Ph.D)--Physics, Georgia Institute of Technology, 2009.<br>Committee Chair: M. R. Flannery; Committee Member: John Wood; Committee Member: Michael Schatz; Committee Member: Rigoberto Hernandez; Committee Member: Turgay Uzer. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Viteau, Matthieu. "Pompage optique et refroidissement laser de la vibration de molecules froides." Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00367369.
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Cette thèse présente différentes études sur la formation et la détection de molécules froides. Différents états moléculaires de grandes élongations, pour la molécule Cs2, sont étudié par spectroscopie de photoassociation et d'ionisation. Ces différentes études ont permis d'affiner notre compréhension des mécanismes de photoassociation d'atomes froids formant des molécules dans l'état fondamental triplet (a 3Σu+).<br />Une détection non sélective a été développée, pour la recherche de mécanismes de formation de molécules froides dans l'état fondamental singulet avec peu de vibration. Avec cette nouvelle détection, un nouveau mécanisme de formation de molécules par photoassociation d'atomes froids de césium a été trouvé. Celui-ci permet de former efficacement des molécules dans une distribution de niveaux avec très peu de vibration dans l'état fondamental (X 1Σg+).<br />En utilisant un laser femtoseconde (large spectralement) façonné, un refroidissement vibrationnel des molécules a été démontré, permettant la formation de molécules froides sans vibrations. Le laser femtoseconde, permet d'exciter les nombreux niveaux vibrationnels, créés par photoassociation, il réalise ainsi un pompage optique des molécules. Le laser est façonné de manière à rendre l'état de vibration zéro, noir pour ce laser, et ainsi accumuler toutes les molécules vers ce seul état. <br />Ce résultat est également simulé par un model théorique simple. Cette simulation permet de généraliser l'idée au refroidissement de la rotation des molécules. <br /><br />Une partie (résumée) présente, en s'appuyant sur les différents articles publiés, les études sur les interactions dipôle-dipôle, à grandes portées, entre atomes de Rydberg.
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Piotrowicz, Michal J. "Ultracold Rydberg atoms." Thesis, Open University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.530495.
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Nguyen, Thanh Long. "Study of dipole-dipole interaction between Rydberg atoms : toward quantum simulation with Rydberg atoms." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066695/document.
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La simulation quantique offre un moyen très prometteur pour comprendre les systèmes quantiques corrélés macroscopiques. De nombreuses plateformes expérimentales sont en cours d'élaboration. Les atomes de Rydberg sont particulièrement intéressants grâce à leur forte interaction dipolaire de cours portée. Dans notre manip, nous préparons et manipulons des ensembles d'atomes de Rydberg excités à partir d'un nuage atomique ultra-froid piégé magnétiquement sur une puce à atome supraconductrice. La dynamique de l'excitation est contrôlée par le processus d'excitation du laser. Le spectre d'énergie d'interaction atomique des N corps est mesuré directment par spectroscopie micro-onde. Dans cette thèse, nous développons un modèle Monte Carlo rigoureux qui nous éclaire sur le processus d'excitation. En utilisant ce modèle, nous discutons de la possibilité de réaliser des simulations quantiques du transport d'énergie sur une chaîne 1D d'atomes de Rydberg de faible moment angulaire. De plus, nous proposons une plateforme innovante pour la réalisation de simulations quantiques. Elle repose sur une approche révolutionnaire basée sur un ensemble d'atomes de Rydberg dont le temps de vie est extrêmement long, qui interagissent fortement et qui sont piégés par laser. Nous présentons les résultats de simulations numériques et nous discutons du large éventail de problèmes qui peuvent être traités avec le modèle proposé<br>Quantum simulation offers a highly promising way to understand large correlated quantum systems, and many experimental platforms are now being developed. Rydberg atoms are especially appealing thanks to their strong and short-range dipole-dipole interaction. In our setup, we prepare and manipulate ensembles of Rydberg atoms excited from an ultracold atomic cloud magnetically trapped above a superconducting chip. The dynamics of the Rydberg excitation can be controlled through the laser excitation process. The many-body atomic interaction energy spectrum is then directly measured through microwave spectroscopy. This thesis develops a rigorous Monte Carlo model that provides an insight into the excitation process. Using this model, we discuss a possibility to explore quantum simulations of energy transport in a 1D chain of low angular momentum Rydberg atoms. Furthermore, we propose an innovative platform for quantum simulations. It relies on a groundbreaking approach, based on laser-trapped ensemble of extremely long-lived, strongly interacting circular Rydberg atoms. We present intensive numerical results as well as discuss a wide range of problems that can be addressed with the proposed model
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Flynn, Emma L. "Reactive scattering of Rydberg atoms." Thesis, Durham University, 2008. http://etheses.dur.ac.uk/2503/.
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A state-of-the-art crossed molecular beam experiment to study the dynamics of bimolecular reactions of electronically highly excited atoms and molecules has been developed. This was primarily designed to investigate the reaction of highly excited Rydberg hydrogen atoms with D(_2) molecules. This reaction is of special interest as it can be compared to the ion-molecule reaction H(^+) + D(_2), using the free electron model and this reaction acts as a benchmark to theoreticians in the quest to understand more complex reactions. The equipment has been calibrated and tested using the well known photodissociation of HI. The initial reactive scattering ion images for H* + D(_2) reaction have been recorded. It was hoped that it would be possible to extract state-to-state differential cross sections; however, to date sufficient resolution has not been achieved, and reasons for this are explored in this study. An overview of the suitability of the prototype molecular wire 1, 4- bis(phenylethynyl)benzene is also included. In this study UV spectra resolving the torsional motion of the benzene rings have been produced using the technique of cavity ring-down spectroscopy.
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Mazurenko, Anton. "Optical imaging of Rydberg atoms." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78519.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 109-111).<br>We present an experiment exploring electromagnetically induced transparency (EIT) in Rydberg atoms in order to observe optical nonlinearities at the single photon level. ⁸⁷Rb atoms are trapped and cooled using a magneto-optical trap (MOT) and a far off resonance dipole trap (FORT). Once the system is prepared, a ladder EIT scheme with Rydberg atoms is used to map the photon field onto the ensemble. The powerful dipole interaction between Rydberg atoms allows the system to exhibit many-body quantum mechanical effects. We also describe an imaging method to observe the Rydberg blockade. Last of all, we present a preliminary measurement of EIT in a Rydberg system. In this measurement, the transmission shows sensitivity to the applied photon flux, and exhibits temporal correlations in the photons exiting the EIT medium.<br>by Anton Mazurenko.<br>S.B.
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Laburthe-Tolra, Bruno. "Atomes, molecules et plasmas ultra-froids : - transition d'un gaz de rydberg gele vers un plasma ultra-froid. - controle de collisions de photoassociation dans des schemas de resonance de feshbach et de transition raman stimulee." Paris 11, 2001. http://www.theses.fr/2001PA112137.
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Nous avons observe l'evolution spontanee d'un gaz de rydberg gele vers un plasma ultra-froid neutre. Les atomes de rydberg sont excites dans un piege magneto-optique. Certains d'entre eux sont ionises du fait de collisions ou de l'absorption du rayonnement du corps noir. Il se cree une charge d'espace. Lorsque celle-ci est suffisament profonde, des electrons sont pieges. Il se produit un phenomene d'ionisation en avalanche de tous les atomes de rydberg restant. Dans la reaction de photoassociation, deux atomes en collision absorbent un photon et forment une molecule electroniquement excitee. Le taux de photoassociation mesure dans nos conditions experimentales est de 0,1 a 5 s - 1 par atome. La spectroscopie de photoassociation est un outil puissant pour la determination des parametres collisionnels. Ainsi, les modulations d'intensite de spectres de photoassociation nous ont permis de determiner la longueur de diffusion triplet du cesium, et d'observer la modification de la longueur de diffusion des atomes de cesium polarises dans l'etat f = 3 m f = 3 au voisinage d'une resonance de feshbach. La reaction de photoassociation conduit a la possibilite de former des molecules froides par desexcitation radiative des molecules excitees. Les mecanismes favorables a la formation de molecules froides reposent sur l'existence de niveaux moleculaires excites pour lesquels la probabilite de presence a courte distance interatomique est importante. De maniere a produire des molecules froides toutes dans le meme niveau ro-vibrationnel, nous avons realise une experience de photoassociation raman stimulee, qui consiste a stimuler la desexcitation radiative des molecules excitees vers un niveau unique du fondamental. Un taux de formation de molecules froides de 10 5 s - 1 a ete mesure. Enfin, nous avons realise un piege magnetique pour les molecules froides dans l'etat triplet de plus basse energie. Le temps de vie du piege a molecules est de l'ordre d'une seconde.
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Smith, Robert Alan Lundie. "Electron dynamics in Rydberg molecules." Thesis, King's College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404481.
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Thwaite, Simon James. "Simulations of systems of cold Rydberg atoms." Thesis, University of Oxford, 2012. https://ora.ox.ac.uk/objects/uuid:454e438d-2a3c-4c91-b1d4-2c594cbab2ce.
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The past three decades have seen extraordinary progress in the manipulation of neutral atoms with laser light, to the point where it is now routine to trap and cool both individual atoms and entire atomic clouds to temperatures of only a few tens of nanoKelvin in a controlled and repeatable fashion. In this thesis we study several applications of Rydberg atoms - atoms with an electron in a highly excited state - within such ultracold atomic systems. Due to their highly-excited electron, Rydberg atoms have a number of exaggerated properties: in addition to being physically large, they have long radiative lifetimes, and interact strongly both with one another and with applied external fields. Rydberg atoms consequently find many interesting applications within ultracold atomic physics. We begin this thesis by analysing the way in which a rubidium atom prepared in an excited Rydberg state decays to the ground state. Using quantum defect theory to model the wavefunction of the excited electron, we compute branching ratios for the various decay channels that lead out of the Rydberg states of rubidium. By using these results to carry out detailed simulations of the radiative cascade process, we show that the dynamics of spontaneous emission from Rydberg states cannot be adequately described by a truncated atomic level structure. We then investigate the stability of ultra-large diatomic molecules formed by pairs of Rydberg atoms. Using quantum defect theory to model the electronic wavefunctions, we apply molecular integral techniques to calculate the equilibrium distance and binding energy of these molecular Rydberg states. Our results indicate that these Ryberg macro-dimers are predicted to show a potential minimum, with equilibrium distances of up to several hundred nanometres. In the second half of this thesis, we present a new method of symbolically evaluating functions of matrices. This method, which we term the method of path-sums, has applications to the simulation of strongly-correlated many-body Rydberg systems, and is based on the combination of a mapping between matrix multiplications and walks on weighted directed graphs with a universal result on the structure of such walks. After presenting and proving this universal graph theoretic result, we develop the path-sum approach to matrix functions. We discuss the application of path-sums to the simulation of strongly-correlated many-body quantum systems, and indicate future directions for the method.
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Faoro, Riccardo. "Few-body interactions in cold Rydberg atoms." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS180/document.
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L’objectif de cette thèse est l’étude des différents aspects de l’interaction à quelques corps entre des atomes de Rydberg froids. Cette thèse a été réalisée dans le cadre d’une cotutelle entre l’Université Paris-Saclay et l’Université de Pise en travaillant sur deux différents montages expérimentaux sur des atomes de Rydberg froids : respectivement sur le Cs au Laboratoire Aimé Cotton et sur le Rb au département de Physique de l’Université de Pise. Au Laboratoire Aimé Cotton nous avons démontré l’existence des nouvelles interactions à quelques corps dans un gas gelé d’atomes de Rydberg. Ces nouvelles résonances sont la généralisation des résonances de Förster bien connues dans le domaine des atomes de Rydberg. Ces résonances agissent sur les degrés de liberté interne des atomes de Rydberg et ont l’effet d’un transfert résonant d’énergie et de population comme dans le cas des FRET (Fluorescence Resonance Energy Transfer). Comme dans le cas de la résonance de Förster à deux corps, les résonances FRET à trois corps sont accordées à la résonance avec un champ électrique externe et peuvent être observées pour différents nombres quantique principaux. Les effets à trois corps sont observés en absence de tout effet à deux corps et sont qualifiés de Borroméens. La présence d’un champ externe peut générer d’autres résonances entre atomes de Rydberg qui sont interdites en absence de champ électrique. Ces résonances, qu’on peut qualifier des résonances quasi-interdites, sont dues à un couplage dipole-dipole de type Förster. Nous avons identifié toutes ces résonances liées au couplage entre les niveaux de multiplicité de n différents.Dans le montage expérimental à Pise on a étudié les effets mécaniques liés à la répulsion van der Waals entre atomes de Rydberg. Nous avons étudié l’expansion due à l’interaction van der Waals dans une chaîne 1D des atomes de Rydberg de Rb qui ont étés excités avec une excitation laser hors résonance. La comparaison entre les différents désaccords de l’excitation laser démontre le rôle central joué par l’interaction van der Waals<br>The aim of this thesis is to investigate different aspects of few-body interactions in cold Rydberg atoms. It has been realized in a co-tutelle program between the University of Paris-Saclay and the University of Pisa working on two different experimental set ups: one at Laboratoire Aimé Cotton on cold Cs Rydberg atoms and a second at Physics Department of Pisa on cold Rb Rydberg atoms. In Laboratoire Aimé Cotton we demonstrated the existence of new few-body interactions we observed in a frozen Rydberg gas of Cs atoms. These new resonances are a generalization of already known two-body Förster resonances. They act on the internal degrees of freedom of the Rydberg atoms leading to a resonant energy transfer analogous to the one in FRET (Fluorescence Resonance Energy Transfer). In analogy with Förster resonance, three-body FRETs are tuned with an external electric field and can be observed for different principal quantum number. The three-body interaction appeared in the absence of any two-body ones and for this reasons it has a Borromean character. The presence of this external electric field leads to additional resonances between Rydberg atoms supposedly forbidden. These resonances, we call quasi-forbidden Förster resonances, are due to dipole-dipole interaction as in the case of Förster resonance. We investigated these resonances finding a large number close to the allowed two-body and three-body FRET. A precise study was necessary in order to identify and discriminate these resonances from the allowed ones.In the experiment in Pisa we instead focus our attention on the mechanical effect of van der Waals repulsion between Rydberg atoms. We studied the spatial expansion due to a van der Waals interaction in a 1D chain of Rb Rydberg atoms excited with an off-resonant laser excitation. The comparison of the spatial expansion for different detuning of the laser excitation reveals the central role of the van der Waals interaction whose strength is equal to the detuning of the laser excitation
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So, Eric. "Interaction of Rydberg hydrogen atoms with metal surfaces." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:53984973-1766-45cc-8bcf-055be714ed73.
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This thesis presents a theoretical and experimental investigation of the interaction of electronically excited Rydberg hydrogen atoms with metal surfaces and the associated charge-transfer process. As a Rydberg atom approaches a metal surface, the energies of the Rydberg states are perturbed by the surface potential generated by the image charges of the Rydberg electron and core. At small atom-surface separations, the Rydberg atom may be ionised by resonant charge transfer of the Rydberg electron to the continuum of delocalised unoccupied metal states, with which the Rydberg electron is degenerate in energy. Typically, this ‘surface ionisation’ can be measured by extracting the remaining positively charged ion-cores with externally applied electric fields. By applying various levels of theory, from classical to fully time-dependent quantum calculations, this thesis explores various experimentally relevant effects on the charge-transfer process, such as the magnitude and direction of the externally applied electric field, the atom collisional velocity, the presence of local surface stray fields and electronically structured surfaces. The theoretical results give insight into the previous experimental work carried out for the xenon atom and hydrogen molecule, and point out some of the fundamental differences from the hydrogen atom system. Experiments involving Rydberg hydrogen atoms incident on an atomically flat gold surface, a rough machined aluminium surface and a single crystal copper (100) surface are presented, providing for the first time the opportunity to make a quantitative comparison of theory and experiments. The ability to control the critical distance at which charge-transfer occurs is demonstrated by using Rydberg states of varying dimensions and collisional velocities. By changing the collisional angle of the incident Rydberg beam, the effect of Rydberg trajectory is also investigated. By manipulating the polarisation of the Rydberg electron with electric fields, genuine control over the orientation of the electron density distribution in the charge-transfer process is demonstrated. This property was predicted by the theory and should be unique to the hydrogen atom due to its intrinsic symmetry. By reversing the direction of the electric field with respect to the metal surface, electrons rather than positive ions are detected, with ionisation dynamics that appear to be very different, as predicted by quantum calculations. Experiments involving the single crystal Cu(100) surface also suggests possible resonance effects from image states embedded in the projected bandgap which are shown from quantum calculations to play an important role in the surface charge transfer of electronically structured metal substrates. The experimental technique developed in this work provides some exciting future applications to study quantum confinement effects with thin films, nanoparticles and other bandgap surfaces. The ability to control the Rydberg orbital size, electronic energy, collisional velocity and orientation in the charge-transfer process will provide novel ways of probing the surface’s electronic and physical structure, as well as being a valuable feature in offering new opportunities for controlling reactive processes at metallic surfaces.
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Zhao, Yongkai. "Cold atoms and molecules." Thesis, Heriot-Watt University, 2012. http://hdl.handle.net/10399/2688.
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The ability to cool and trap atoms has revolutionized atomic and ultra-cold physics. Molecular physics is currently undergoing a similar transformation. This thesis aims to research a general cooling method that will be applicable to wide range of molecular and atomic species and other particles. We studied the dynamics of molecules in optical fields, focusing in particular on exploring the molecular self-organisation phenomena in optical cavities to cool molecular ensembles to sub-mK temperatures. Firstly, the general model of cavity cooling from atoms to molecules and the dynamics of a particle in a single cavity mode were discussed. We extended the existing cooling scheme for two-level atoms to an ensemble of multi-level molecules. Then we studied the spatial dynamics of molecules in the new parameter conditions, focusing in particular on exploring the molecular self-organisation phenomena in optical cavities to cool molecular ensembles to sub-mK temperatures. The scheme complements well with our present experimental work on the deceleration and focusing of cold molecules and can extend our present capability to simultaneously cool and trap a large cold molecular ensemble. For simulation of a large ensemble of molecules, we proposed a new statistical model based on the Boltzmann equation beside the traditional discrete model and studied two solution methods. The comparison of the theory and numerical simulations between discrete model and statistical model showed a good agreement, which validated this new model. We then explored the scaling laws with a view to the self-organization and cooling of a large ensemble of species. We studied the cooling of a CN molecular cloud of the density 1013/cm3, with an initial temperature at 10 mK in an optical cavity. We found that more than a third of the molecules are stably trapped by the intracavity field and the final temperature is below 1mK. We discussed the scaling laws in the case when a large ensemble of species is involved. Finally we argue that cavity cooling using a far off-resonant laser source can be a general cooling method that is applicable to any particles and studied the probability and conditions.
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Baluktsian, Thomas [Verfasser]. "Rydberg interaction between thermal atoms: Van der Waals-type Rydberg-Rydberg interaction in a vapor cell experiment / Thomas Baluktsian." München : Verlag Dr. Hut, 2014. http://d-nb.info/1047994690/34.
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Thoumany, Pierre. "Optical Spectroscopy and Cavity QED Experiments with Rydberg Atoms." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-130845.
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Tignone, Edoardo. "Cavity quantum electrodynamics : from photonic crystals to Rydberg atoms." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF008/document.
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Dans le premier chapitre de la thèse, nous étudions la possibilité d’améliorer le couplage opto- mechanique photon-phonon entre le mode de résonance d’une cavité Fabry-Pérot de haute finesse et les vibrations mécaniques des éléments diélectriques (membranes) à l’intérieur de la cavité. En introduisant un défaut quadratique dans la disposition des membranes, nous montrons que le deux couplages (linéaire et quadratique) augmentent. Enfin, nous proposons un modèle très simple avec lequel on cherche à simuler un cristal photonique quasipériodique. Dans le deuxième chapitre de cette thèse, nous présentons nos résultats de recherche sur le transport d’excitons à travers une cavité visant à augmenter l’efficacité du transport. Le modèle que l’on étudie est une chaîne unidimensionnelle d’atomes froids comprenant chacun deux niveaux énergétiques. Grâce au couplage entre exciton et photon, ces deux quanta s’hybrident et forment deux branches de polariton à l’intérieur de la cavité. Nous avons observé qu’à résonance avec un des deux modes de polariton, on peut transmettre l’exciton via le mode polaritonique dans un temps très court. En outre, le désordre n’affecte la propagation excitonique que de façon algébrique. Dans le troisième chapitre de cette thèse, nous présentons nos résultats de recherche sur la réalisa- tion d’interactions entre photons grâce à la médiation d’atomes ultrafroids piégés dans un réseaux optique unidimensionnelle et placés à l’intérieur d’une fibre à cristaux photoniques. Nous avons détecté un régime dans lequel on peut réaliser le “bunching” photon-photon.Dans le quatrième et dernière chapitre de cette thèse, nous étendons les résultats du chapitre précédent aux atomes de Rydberg<br>In the first chapter of this thesis, we study a quasiperiodic array of dielectric membranes inside a high-finesse Fabry-Pérot cavity. We work within the framework of the transfer matrix formal- ism. We show that, in a transmissive regime, the introduction of a quadratic spatial defect in the membrane positions enhances both the linear and quadratic optomechanical couplings between optical and mechanical degrees of freedom. Finally, we propose a theoretical model to simulate a one-dimensional quasiperiodic photonic crystal. In the second chapter of this thesis, we consider the problem of the transport of an exciton through a one-dimensional chain of two-level systems. We embed the chain of emitters in a transverse optical cavity and we show that, in the strong coupling regime, a ultrafast ballistic transport of the exciton is possible via the polaritonic modes rather than ordinary hopping. Due to the hybrid nature of polaritons, the transport efficiency is particularly robust against disorder and imperfections in the system. In the third chapter of this thesis, we consider an ordered array of cold atoms trapped in an optical lattice inside a hollow-core photonic crystal fiber. We study photon-photon interactions mediated by hard-core repulsion between excitons. We show that, in spite of underlying repulsive interac- tion, photons in the scattering states demonstrate bunching, which can be controlled by tuning the interatomic separation. We interpret this bunching as the result of scattering due to the mismatch of the quantization volumes for excitons and photons, and discuss the dependence of the effect on experimentally relevant parameters. In the fourth chapter of the thesis, we extend the results of the previous chapter to Rydberg atoms
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Busche, Hannes. "Contactless quantum non-linear optics with cold Rydberg atoms." Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12238/.
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Rydberg quantum optics achieves optical non-linearities at the single-photon level by mapping the strong dipolar interactions between Rydberg atoms in cold atomic gases onto light fields using electromagnetically-induced transparency and photon storage. The non-linearities are a direct consequence of the long-range character of the interaction which allows a single photon to modify the optical response in a volume containing many atoms. In this thesis, the long-range character of the resulting effective photon-photon interaction is directly observed as photons propagating in non-overlapping optical modes are stored as collective Rydberg excitations in adjacent and non-overlapping microscopic clouds of 87Rb atoms. While stored, van-der-Waals interactions imprint spatially non-uniform phase shifts in the collective excitations. These distort the photons' retrieval modes resulting in anti-correlated retrieval between the original modes. In this first demonstration of contactless effective interactions between photons, these effects are observed between photons separated by more than 15 times their wavelength, well above the optical diffraction limit. This represents a promising step towards the implementation of scalable, multichannel quantum optical devices such as quantum gates. The experiments are enabled by a new, specialised experimental setup centred around a pair of in-vacuo aspheric lenses. These provide optical resolution of order 1 µm to optically trap and address the ensembles separated by distances well below the range of Rydberg interactions. The ensembles are prepared in approximately 100 ms thanks to efficient loading of a magneto-optical trap (MOT) from an atomic beam produced by a 2D MOT. Combined with the ability to recycle the ensembles > 20000 times, effective cycle times exceeding 100 kHz enable the acquisition of large datasets for the analysis of photon statistics within a matter of minutes.
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Fletcher, Robert S. "Three-body recombination and Rydberg atoms in ultracold plasmas." College Park, Md. : University of Maryland, 2008. http://hdl.handle.net/1903/8086.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.<br>Thesis research directed by: Dept. of Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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McCormack, Elin A. "Ionisation of hydrogen Rydberg molecules at surfaces." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543033.
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Caliri, Lucas Larcher. "Processos binários em átomos de Rydberg." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-18062008-113214/.
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O presente trabalho procura investigar alguns dos processos colisionais de átomos de Rydberg ultrafrios. Utilizando uma armadilha magneto-óptica (MOT), foi possível aprisionar átomos de 85Rb, um elemento alcalino metálico, numa região da ordem de lmn a temperaturas da ordem de poucas centenas de ?K, regime chamado de \"ultrafrio\" na literatura. Os átomos de 85Rb são então excitados para estados de alto número quântico principal, também chamados de estados de Rydberg, através de um laser pulsado. Nesses estados, os átomos apresentam propriedades exageradas devido ao tamanho da órbita do elétron de valência, sendo uma delas os potenciais de longo-alcance. Em nossos experimentos, após a excitação, são detectados átomos em estados vizinhos ao originalmente excitado, evidenciando a existência de transições. Como esses estados são muito próximos em energia, a presença de potenciais de longo alcance pode fazer a energia de um par de átomos de Rydberg no seu estado inicial ficar ressonante com a energia do mesmo par numa combinação de outros estados, tornando então possível transições para esses estados. Nosso estudo visa quantificar de certa forma essas observações, assim como estimar a importância do movimento desses átomos nas transições observadas.<br>This dissertation seeks to address some of the characteristics of collisional processes in ultracold Rydberg atoms. With a Maqneto-Optical Trap (MOT), we trapped a sample of 85Rb, an alkaline metal element, in a region of about lmm at a temperature of a few hundreds of ?K, known in the literature as the \"ultracold\" regime. The 85Rb atoms are then excited to high principal quantum number states, also known as Rydberg states, with a pulsed laser. In these states, the atoms present exaggerated properties due to the large valence electron orbit, such as long-range potentials in our experiments, after excitation, we have detected atoms in neighboring states to the originally excited state, an evidence of atomic transitions. Since these states have similar energy, the presence of long-range potentials can make the energy of a pair of atoms in the initial state be resonant with the energy of the same pair in a combination of different states, making it possible to have transitions to these nearby states. Our work tries to quantify these observations, as well as to gauge the role of atomic movement in these transitions.
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Topçu, Türker. "Time dependent studies of fundamental atomic processes in Rydberg atoms /." Auburn, Ala., 2007. http://repo.lib.auburn.edu/07M%20Dissertations/TOPCU_TURKER_31.pdf.
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Abel, Richard Philip. "Coherent excitation of ultracold atoms between ground and Rydberg states." Thesis, Durham University, 2011. http://etheses.dur.ac.uk/1405/.
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This thesis describes the development of an experiment to study coherent population transfer between ground states, and between ground and Rydberg states, in ultracold atoms. In order to study coherent transfer between hyperfine ground states a pair of phase stable Raman beams is required. Both beams are derived from a single master laser before being spatially separated into individual components using a novel Faraday filtering technique. The frequency dependent Faraday effect in an isotopically pure thermal vapour is exploited to rotate the plane of polarisation of each Raman component such that they may be separated using a polarising beam splitter. The Raman beams are applied to a sample of ultracold atoms and evidence of coherent population transfer is observed. Rydberg states offer an ideal tool for electrometry; the electric field induced Rydberg energy level shift scales with the seventh power of the principle quantum number. Electromagnetically induced transparency (EIT) is used to map Rydberg energy level shifts onto a ground state transition. EIT in a thermal vapour cell also provides a novel method of stabilising the Rydberg coupling laser. The Rydberg energy level shift is highly sensitive to the electric field produced by adsorbates bonded to a nearby dielectric surface. These effects are found to be time dependent and can be eliminated if the electric field is applied transiently. The measured electric field is compared to that calculated by numerical solution of Laplace's equation; the bulk dielectric is found to have a strong effect on the local electric field experienced by the atoms. The exaggerated properties of Rydberg states make these systems ideal for quantum information processing and precision electrometry.
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Hamadeh, Lama. "Ultracold gases of Rydberg-dressed atoms in multi-well traps." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/55953/.
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Rydberg-dressed ground state atoms are atoms with an electron off-resonantly excited to a very high energy state, i.e., a state of high principal quantum number n ≫ 1. This thesis investigates the quantum dynamics of interacting Rydberg-dressed ground state atoms trapped in several multi-well potential traps. Rydberg atoms are atoms with exaggerated properties. One of their most interesting properties is that they exhibit a strong and long-ranged interaction that can be tuned leading to a variety of different quantum behaviours. My work focuses on studying the effects of these interacting atoms when loaded in multi-well potential traps. Generally, multi-well systems are considered as the simplest example of a finite optical lattice structure. For this reason, this thesis covers three research topics that examine the effects of long-range interaction on Rydberg-dressed atoms trapped in several potential confinements. I begin, in the introduction, by discussing the theoretical background of relevance to this work. It starts with presenting the physics of Bose-Einstein condensate. Then, the fundamentals of the interaction between two-level atom and light are analytically studied. This study has the purpose of understanding both; the dressed interacting atoms and optical lattices. The definition, characteristics, and the nature of the interaction between Rydberg atoms are analysed afterwards. The second chapter examines the dynamics of an ensemble of interacting Rydberg- dressed atoms trapped in static, i.e., time-independent, multi-well potentials using a mean-field theoretical approach. I choose one-dimensional double- and triple-well in addition to a two-dimensional quadruple-well potentials. The time-dependent non-linear Gross-Pitaevskii equation is used to numerically explore the ensemble's quantum dynamics. Solving the dynamical differential equations along with tuning the strength of the applied long-range interaction shows that the behaviour of non-interacting Rydberg-dressed atoms does not differ conceptually according to the geometry of the trapping potential. However, this changes when the interactions are switched on where the shape of the confinement leads to interesting outcomes especially in the non-linear interacting limit, such as macroscopic quantum self-trapping. After investigating an ensemble of interacting Rydberg-dressed atoms in static multi-well potential traps, the second research topic examines the dynamical evolution of these atoms when loaded in a finite optical lattice using the extended Bose-Hubbard model. In this chapter, the atoms ensemble is assumed to be in a superfluid state where I investigate both, the order parameter when the Rydberg excitation laser is applied and the interference pattern of the condensates in different dimensions. The study shows the emerging long-range interactions lead to a rapid collapse of the superfluid order parameter and in general allow only for partial revivals. In addition, the interference experiments can directly reveal the interaction between Rydberg-dressed atoms. In the fourth chapter, the dynamics of Rydberg-dressed atoms trapped in a dynamical, i.e., time-dependent, potential confinement is presented. The dynamical trap is constructed such that it begins as a harmonic oscillator and ends as a double- well potential. The analysis investigates an ensemble of contact-interacting atoms via the time-dependent non-linear GP equation.
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Vaillant, Christophe Louis J. "Long-range interactions in one- and two-electron Rydberg atoms." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10594/.
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We present calculations of long-range interactions in Rydberg atoms, with a focus on the dipole-dipole interactions of strontium Rydberg states. The growing use of Rydberg states in the field of cold atoms necessitates a more detailed understanding of the effects of dipole-dipole interactions, which are currently being investigated in a number of research groups worldwide. Calculations of long-range interactions in Rydberg states of caesium, cal- cium, rubidium, strontium and ytterbium are presented. By taking the one active electron approximation we develop consistent models of these long- range interactions, and construct a survey of the Rydberg state dipole-dipole interactions and quadrupole-quadrupole interactions. We compare the inter- actions between series and between atoms, highlighting the importance of certain series for applications suggested in previous works. In order to include two-electron effects in the description of dipole-dipole interactions in divalent atoms, we use multichannel quantum defect theory (MQDT) to develop models of the Rydberg series of strontium. We use an empirical reactance matrix formalism, where the reactance matrix is fitted to reproduce experimentally measured values of the bound state energy levels. Models are found for all series of strontium with L ≤ 3. We extend the MQDT formalism to the description of the natural radiative lifetimes of strontium, where the perturbers are found to have a large quenching effect on these lifetimes. By incorporating the MQDT description of the Rydberg states of strontium into the calculation of dipole-dipole interactions, we find a spin-forbidden two-atom resonance in the 3D2 states of strontium. We consider a one- dimensional lattice of strontium atoms, and find that the internal dynamics of the Rydberg atoms demonstrates spin transport for large lattice spacings and a separation of the spin and total angular momentum dynamics for small lattice spacings. Spin-angular momentum separation (analogous to spin-charge separation in condensed matter) in strontium Rydberg atoms may have uses in the investigation of one-dimensional Fermi gases and their description using Luttinger liquid theory.
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Shibata, Masahiro. "Microwave Single-Photon Detection with Rydberg Atoms at Low Temperature." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147804.
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Wintermantel, Tobias Martin. "Complex systems dynamics in laser excited ensembles of Rydberg atoms." Thesis, Strasbourg, 2021. http://www.theses.fr/2021STRAE001.
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Dans cette thèse, je présente des résultats expérimentaux et théoriques montrant qu’un gaz ultra-froid sous excitation laser aux états de Rydberg offre une plateforme contrôlable pour l’étude d’une intéressante dynamique complexe qui peut émerger dans les systèmes drivés-dissipatifs. Les conclusions peuvent être résumées selon les trois idées principales suivantes : (i) La découverte de la criticité auto-organisée dans notre système de Rydberg sous excitation facilitée peut aider à répondre à la question suivante : Pourquoi le comportement invariant d’échelle est si répandu dans la nature ? (ii) Un lien frappant est établi entre la croissance de la loi de puissance du nombre d’excitation de Rydberg et la propagation des épidémies. L’importance de l’hétérogénéité dans le réseau Rydberg émergeant et les effets Griffith associés permettent d’expliquer l’observation de lois de puissance non universelles. (iii) Une nouvelle mise en oeuvre d’automates cellulaires quantiques est proposée en utilisant des réseaux atomiques associés à des champs laser multifréquences. Cela fournit un cadre naturel pour étudier la relation entre les processus microscopiques et la dynamique globale, où des règles spéciales sont trouvées pour générer des états enchevêtrés pour des applications en métrologie et en informatique quantique<br>In this thesis I present experimental and theoretical results showing that an ultracold gas under laser excitation to Rydberg states offers a controllable platform for studying the interesting complex dynamics that can emerge in driven-dissipative systems. The findings can be summarized according to the following three main insights: (i) The discovery of self-organized criticality (SOC) in our Rydberg system under facilitated excitation via three signatures: self-organization of the density to a stationary state; scale invariant behavior; and a critical response in terms of power-law distributed excitation avalanches. Additionally, we explore a mechanism inherent to our system which stabilizes the SOC state. We further investigate this stabilization via a controlled, variable driving of the system. These analyses can help answer the question of why scale invariant behavior is so prevalent in nature. (ii) A striking connection between the power-law growth of the Rydberg excitation number and epidemic spreading is found. Based on this, an epidemic network model is devised which efficiently describes the collective excitation dynamics. The importance of heterogeneity in the emergent Rydberg network and associated Griffiths effects provide a way to explain the observation of non-universal power laws.(iii) A novel quantum cellular automata implementation is proposed using atomic arrays together with multifrequency laser fields. This provides a natural framework to study the relation between microscopic processes and global dynamics, where special rules are found to generate entangled states with applications in quantum metrology and computing
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Tuorila, J. (Jani). "Spectroscopy of artificial atoms and molecules." Doctoral thesis, Oulun yliopisto, 2010. http://urn.fi/urn:isbn:9789514262135.
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Elementary experiments of atomic physics and quantum optics can be reproduced on a circuit board using elements built of superconducting materials. Such systems can show discrete energy levels similar to those of atoms. With respect to their natural cousins, the enhanced controllability of these ‘artificial atoms’ allows the testing of the laws of physics in a novel range of parameters. Also, the study of such systems is important for their proposed use as the quantum bits (qubits) of the foreseen quantum computer.
In this thesis, we have studied an artificial atom coupled with a harmonic oscillator formed by an LC-resonator. At the quantum limit, the interaction between the two can be shown to mimic that of ordinary matter and light. The properties of the system were studied by measuring the reflected signal in a capacitively coupled transmission line. In atomic physics, this has an analogy with the absorption spectrum of electromagnetic radiation. To simulate such measurements, we have derived the corresponding equations of motion using the quantum network theory and the semi-classical approximation. The calculated absorption spectrum shows a good agreement with the experimental data. By extracting the power consumption in different parts of the circuit, we have calculated the energy flow between the atom and the oscillator. It shows that, in a certain parameter range, the absorption spectrum obeys the Franck-Condon principle, and can be interpreted in terms of vibronic transitions of a diatomic molecule.
A coupling with a radiation field shifts the spectral lines of an atom. In our system, the interaction between the atom and the field is nonlinear, and we have shown that a strong monochromatic driving results in energy shifts unforeseen in natural or, even, other artificial atoms. We have used the Floquet method to calculate the quasienergies of the coupled system of atom and field. The oscillator was treated as a small perturbation probing the quasienergies, and the resulting absorption spectrum agrees with the reflection measurement.
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Whitehouse, David Benjamin. "Electrical properties of atoms and molecules." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260492.
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Iwata, Koji. "Positron annihilation on atoms and molecules /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 1997. http://wwwlib.umi.com/cr/ucsd/fullcit?p9811796.
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Mukherjee, Rick. "Strong interactions in alkaline-earth Rydberg ensembles." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-157228.
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Ultra-cold atoms in optical lattices provide a versatile and robust platform to study fundamental condensed-matter physics problems and have applications in quantum optics as well as quantum information processing. For many of these applications, Rydberg atoms (atoms excited to large principal quantum numbers) are ideal due to its long coherence times and strong interactions.
However, one of the pre-requisite for such applications is identical confinement of ground state atoms with Rydberg atoms. This is challenging for conventionally used alkali atoms. In this thesis, I discuss the potential of using alkaline-earth Rydberg atoms for many-body physics by implementing simultaneous trapping for the relevant internal states. In particular, I consider a scheme for generating multi-particle entanglement and explore charge transport in a one dimensional atomic lattice.
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Krupp, Alexander Thorsten [Verfasser]. "D-state Rydberg electrons interacting with ultracold atoms / Alexander Thorsten Krupp." München : Verlag Dr. Hut, 2015. http://d-nb.info/1067708200/34.
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Courtney, Michael W. "Rydberg atoms in strong fields : a testing ground for quantum chaos." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/32633.
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Ribeiro, Sofia. "Atom-surface interactions with Rydberg atoms : an application to hybrid systems." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/24166.
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This thesis focuses on theoretical quantum optics, with special emphasis on developing protocols in which engineered vacuum forces enable one to construct hybrid systems. In these systems, atoms are combined with solid-state devices in order to take advantage of their unique properties such as long coherence times of atoms and flexibility, tunability, scalability, and fast response offered by solid-state systems. Special attention is given to the study of atom-surface interactions with Rydberg atoms, where exact Fano-type diagonalization of the interaction Hamiltonian is obtained showing that, not only do Rydberg atoms suffer energy shifts, the presence of a surface leads to an alteration and admixture of the unperturbed eigenstates. Of particular interest are dispersion forces on graphene systems. We investigate whether and under which circumstances the Casimir-Polder potential between an atom and a graphene-substrate system is dominated by the interaction with graphene such that the effect of the substrate does not play an important role. We also explore the possibility to create a setup where dispersion forces could be use to bend a graphene sheet. Placing an atom close, at distances of a few hundred nanometers, to a free-standing graphene membrane we show that temporal changes in the atomic state change the Casimir-Polder interaction, thereby leading to the creation of a backaction force in the graphene sheet. Finally, we look at nonlinear atom--surface coupling processes with the aim of proposing a hybrid quantum circuit device in which individual field-excitations can be transferred between atoms and surface polaritons on demand. Deeper investigations of nonlinear processes reveal the existence of a sum rule for two-photon spontaneous decay rates that can be simply understood as a redistribution of photonic modes across the frequency spectrum where the total integrated number of modes is still conserved.
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Leseleuc, de kerouara Sylvain de. "Quantum simulation of spin models with assembled arrays of Rydberg atoms." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLO007.
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Des atomes individuels piégés dans des matrices de pinces optiques et excités vers des états de Rydberg forment une plateforme expérimentale prometteuse pour la simulation quantique de modèles de spins. Lors de cette thèse, nous avons d’abord résolu le problème du chargement aléatoire des pièges, seulement 50 % d’entre eux étant chargés avec un atome. Nous avons développé une technique pour préparer des matrices 2D, puis 3D, d’atomes de 87Rb en les déplaçant un par un avec une pince optique mobile contrôlée par ordinateur. Nous avons ensuite réalisé le modèle d’Ising en excitant de manière cohérente les atomes depuis leur état électronique fondamental vers un niveau de Rydberg. Après avoir trouvé un régime optimal où l’interaction dipolaire entre deux atomes de Rydberg se réduit à une énergie de van der Waals, nous avons tenté de préparer adiabatiquement l’état de Néel qui minimise l’énergie d’interaction. Nous avons montré que l’efficacité de préparation étaitlimitée par la décohérence induite par les lasers d’excitation. Nous avons ensuite utilisé un autre régime d’interaction, le couplage dipolaire résonant, pour étudier des modèles de spins de type XY, dont le modèle Su-Schrieffer-Heeger, connu pour sa phase fermionique topologique protégée par une symétrie chirale. Ici, nous avons remplacé les fermions par des particules effectives de type `boson de cœur dur’, ce qui modifie les propriétés de cette phase. Nous avons d’abord retrouvé les propriétés à une particule, comme l’existence d’états de bords à énergie nulle. Nous avons ensuite préparé l’état fondamental à N corps pour un remplissage moitié, et observé sa dégénérescence causée par les états de bords, même en présence d’une perturbation qui lèverait cette dégénérescence dans le cas fermionique. Nous avons expliqué ce résultat par l’existence d’une symétrie plus générale, qui protège la phase bosonique<br>Single atoms trapped in arrays of optical tweezers and excited to Rydberg states are a promising experimental platform for the quantum simulation of spin models. In this thesis, we first solved a long-standing challenge to this approach caused by the random loading of the traps, with only 50% of them filled with single atoms. We have engineered a robust and easy-to-use method to assemble perfectly filled two-dimensional arrays of 87Rb atoms by moving them one by one with a moveable optical tweezers controlled by computer, a technique further enhanced to trap, image and assemble three-dimensional arrays. We then implemented the quantum Ising model by coherently coupling ground-state atoms to a Rydberg level. After finding experimental parameters where the dipole-dipole interaction takes the ideal form of a van der Waals shift, we performed adiabatic preparation of the Néel state. We showed that the coherence time of our excitation lasers limited the efficiency of this technique. We then used a different type of interaction, a resonant dipolar coupling, to implement XY spin models and notably the Su-Schrieffer-Heeger model, known for its fermionic topological phase protected by the chiral symmetry. Here, we used effective hard-core bosons, which modify the properties of the topological phase. We first recovered known properties at the single particle level, such as the existence of localized zero-energy edge-states. Then, preparing the many-body ground state at half-filling, we observed a surprising robustness of its four-fold degeneracy upon applying a perturbation. This result was explained by the existence of a more general symmetry protecting the bosonic phase
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Cayayan, Lyndon Mark D. "Collective Quantum Jumps of Rydberg Atoms Undergoing Two-Channel Spontaneous Emission." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1470410030.
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Kishimoto, Yasuhiro. "Stark structure and field ionization characteristics of highly excited Rydberg atoms." 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149965.
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Zuliani, Alexandre. "Vers la manipulation optique d'atomes ultra-froids d'ytterbium excités dans des états de Rydberg." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS141/document.
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Les propriétés exacerbées des atomes de Rydberg ont permis d'étendre les possibilités offertes par les atomes froids dans la création de gaz d'atomes en très forte interaction, avec des applications notamment en simulations quantiques, dans la physique à N corps ou dans la réalisation de portes quantiques grâce au phénomène de blocage dipolaire. L'utilisation des atomes de Rydberg froids est cependant actuellement limitée par le fait qu'il n'est pas possible de continuer d'appliquer les techniques expérimentales de manipulation optique avec les atomes à un électron actif. L’attention de la communauté des atomes de Rydberg froids s’est donc récemment portée sur les atomes à deux électrons actifs qui offrent la possibilités, une fois l’un des deux électrons excité vers un état de Rydberg, de disposer d’un second électron optiquement actif qu’il va être possible de manipuler par laser. L’objectif de cette thèse est d’étendre les techniques de manipulation optique aux atomes à deux électrons actifs excités dans des états de Rydberg, dans le cas de l’atome d’ytterbium. Elle présente d’une part la conception et l’assemblage du dispositif expérimental permettant l’obtention d’une source d’atomes de Rydberg froids d’ytterbium. A terme, ce montage permettra la manipulation optique de ces atomes de Rydberg. D’autre part, elle présente le développement d’un modèle numérique implémentant la théorie du défaut quantique à plusieurs voies pour permettre la détermination théorique du spectre énergétique de l’ytterbium ainsi que son comportement sous l’effet de perturbations extérieures<br>The exacerbated properties of Rydberg atoms have extended the possibilities offered by cold atoms in creating atomic gases in very strong interaction with applications including quantum simulations in many-body physics or in achieving of quantum gates with the dipole blocking phenomenon. The use of cold Rydberg atoms is however currently limited by the fact that it is not possible to continue to apply the experimental techniques of optical manipulation with the atoms to an active electron. The attention of the Rydberg atoms cold community is recently focused on the two active electron atoms offering possibilities, once one of the two electrons excited to a Rydberg state, to provide a second optically active electron that it will be possible to manipulate with laser light.The objective of this thesis is to extend the optical manipulation techniques to atoms with two active electrons excited in Rydberg states, in the case of the ytterbium atom. It has on the one hand the design and assembly of the experimental apparatus for obtaining a source of cold Rydberg ytterbium atoms. Ultimately, this device will allow the optical manipulation of these Rydberg atoms. Furthermore, it presents the development of a numerical model that implements the multichannel quantum defect theory to the theoretical determination of the energy spectrum of ytterbium and its behavior under the influence of external perturbations