Radio-frequency evaporation in an optical dipole trap

We present an evaporative cooling technique for atoms trapped in an optical dipole trap that benefits from narrow optical transitions. For an appropriate choice of wavelength and polarization, a single laser beam leads to opposite light-shifts in two internal states of the lowest energy manifold. Radio-frequency coupling between these two states results in evaporative cooling at a constant trap stiffness. The evaporation protocol is well adapted to several atomic species, in particular to the case of Lanthanides such as Er, Dy, and fermionic Yb, but also to alkali-earth metals such as fermionic Sr. We derive the dimensionless expressions that allow us to estimate the evaporation efficiency. As a concrete example, we consider the case of $^{162}$Dy and present a numerical analysis of the evaporation in a dipole trap near the $J'=J$ optical transition at 832 nm. We show that this technique can lead to runaway evaporation in a minimalist experimental setup

Formation of H3−_3^- by radiative association of H2_2 and H−^- in the interstellar medium

We develop the theory of radiative association of an atom and a diatomic molecule within a close-coupling framework. We apply it to the formation of H$_3^-$ after the low energy collision (below 0.5 eV) of H$_2$ with H$^-$. Using recently obtained potential energy and permanent dipole moment surfaces of H$_3^-$, we calculate the lowest rovibrational levels of the H$_3^-$ electronic ground state, and the cross section for the formation of H$_3^-$ by radiative association between H$^-$ and ortho- and para-H$_2$. We discuss the possibility for the H$_3^-$ ion to be formed and observed in the cold and dense interstellar medium in an environment with a high ionization rate. Such an observation would be a probe for the presence of H$^-$ in the interstellar medium

Probing quantum criticality and symmetry breaking at the microscopic level

We report on an experimental study of the Lipkin-Meshkov-Glick model of quantum spins interacting at infinite range in a transverse magnetic field, which exhibits a ferromagnetic phase transition in the thermodynamic limit. We use Dysprosium atoms of electronic spin $J=8$, subjected to a quadratic Zeeman light shift, to simulate $2J=16$ interacting spins $1/2$. We probe the system microscopically using single magnetic sublevel resolution, giving access to the spin projection parity, which is the collective observable characterizing the underlying $\mathbb{Z}_2$ symmetry. We measure the thermodynamic properties and dynamical response of the system, and study the quantum critical behavior around the transition point. In the ferromagnetic phase, we achieve coherent tunneling between symmetry-broken states, and test the link between symmetry breaking and the appearance of a finite order parameter.Comment: 13 pages, 13 figure

An atomic Hong-Ou-Mandel experiment

The celebrated Hong, Ou and Mandel (HOM) effect is one of the simplest illustrations of two-particle interference, and is unique to the quantum realm. In the original experiment, two photons arriving simultaneously in the input channels of a beam-splitter were observed to always emerge together in one of the output channels. Here, we report on the realisation of a closely analogous experiment with atoms instead of photons. This opens the prospect of testing Bell's inequalities involving mechanical observables of massive particles, such as momentum, using methods inspired by quantum optics, with an eye on theories of the quantum-to-classical transition. Our work also demonstrates a new way to produce and benchmark twin-atom pairs that may be of interest for quantum information processing and quantum simulation

An atomic Hong-Ou-Mandel experiment

In this thesis, we report the first realisation of the Hong–Ou–Mandel experiment with massive particles in momentum space. This milestone experiment was originally performed in quantum optics: two photons arriving simultaneously at the input ports of a 50:50 beam-splitter always emerge together in one of the output ports. The effect leads to a reduction of coincidence counts which translates into a dip when particles are indistinguishable. We performed the experiment with metastable helium atoms where the specificities of the Micro-Channel-Plate detector allows one to recover the momentum vector of each individual atom.After listing the necessary tools to perform this experiment with atoms, the experimental sequence is discussed and the results are presented. In particular we measured a coincidence count reduction that cannot be explained through any simple classical model. This corresponds to the signature of a two-particle interference, and confirms that our atomic pair source produces beams which have highly correlated populations and are well mode matched. This opens the prospect of testing Bell’s inequalities involving mechanical observables of massive particles, such as momentum, using methods inspired by quantum optics. It also demonstrates a new way to produce and benchmark twin-atom pairs that may be of interest for quantum information processing.Cette thèse décrit l'observation expérimentale de l'effet Hong-Ou-Mandel avec une sourceatomique ultra-froide. L’expérience originale réalisée en 1987 par C. K. Hong, Z. Y. Ou et L. Mandel illustre de façon simple une interférence à deux particules explicable uniquement par la mécanique quantique : deux particules bosoniques et indiscernables, arrivant chacune sur une face d'entrée différente d'une lame semi-réfléchissante ressortent ensemble. Cet effet se traduit par une réduction du taux de détection en coïncidence entre les deux voies de sortie quand les particules arrivent simultanément sur la lame. Cette expérience fut originalement réalisée avec des photons et nous rapportons ici la première mise en oeuvre expérimentale avec des particules massives se propageant dans l’espace libre.Après présentation des différentes techniques nécessaires à sa réalisation, nous décrivons cette expérience et analysons les résultats obtenus. En particulier, la réduction du taux de coïncidence est suffisamment forte pour exclure toute interprétation classique ; l'observation de cet effet constitue une brique fondamentale dans le domaine de l’information quantique atomique

Efeitos da realidade virtual e videogames em escolares acometidos por traumatismo craniano : uma revisão sistemática

Trabalho de Conclusão de Curso (graduação) — Universidade de Brasília, Faculdade de Educação Física, 2019.Introdução: A lesão cerebral traumática é uma das principais causas de incapacidade em todo o mundo. Intervenções baseadas em Videogames e Realidade Virtual tem sido utilizado com sucesso na intervenção terapêutica baseada em exercícios sistematizados para o tratamento de indivíduos acometidos por traumatismos cranianos. Objetivo: Avaliar os efeitos de intervenções baseadas em Realidade Virtual e Videogames em escolares acometidos por traumatismo craniano. Método: Trata-se de um estudo de revisão sistemática da literatura que seguiu as diretrizes do Preferred Reporting Items for Systematic Review and Metaanalyses (PRISMA). Ensaios clínicos aleatorizados (ECA) e estudos prospectivos foram incluídos nesta revisão. Foram selecionadas as seguintes bases de dados para este estudo: Medical Literature Analysis and Retrieval System on-line (MEDLINE) pela Pubmeb, Cochrane library, PEDro e Scientific Electronic Library Online (sciELO). Resultados: Após busca nas bases de dados obtiveram-se 315 estudos, removeu-se as duplicatas resultando em 297 estudos. Realizou-se uma análise por meio do resumo e outros dados em concordância com os critérios de elegibilidade, resultando em 36 estudos para a leitura completa, após identificação dos estudos na integra, resultaram 8 estudos que compõem esta revisão. Conclusão: As tarefas baseadas em videogamers com intervenções sistematizadas apresentaram efeitos mais significativos nas variáveis referentes a atenção e memória de trabalho. Outros desfechos foram relatados no equilíbrio estático e dinâmico. As tarefas baseadas em realidade virtual apresentaram melhoria nos processos seletivos de memória e percepção da função da memóriaIntroduction: Traumatic brain injury is one of the leading causes of disability worldwide. Video-game and Virtual Reality-based interventions have been successfully used in systematic exercise-based therapeutic intervention for the treatment of individuals with head injuries. Objective: To evaluate the effects of interventions based on Virtual Reality and Video Games in schoolchildren with head trauma. Method: This is a systematic literature review study that followed the guidelines of the Preferred Reporting Items for Systematic Review and Metaanalyzes (PRISMA). Randomized controlled trials (RCTs) and prospective studies were included in this review. The following databases were selected for this study: Online Medical Literature Analysis and Retrieval System (MEDLINE) by Pubmeb, Cochrane library, PEDro and Scientific Electronic Library Online (sciELO). Results: After searching the databases, 315 studies were obtained, duplicates were removed resulting in 297 studies. An analysis was performed by means of the abstract and other data in accordance with the eligibility criteria, resulting in 36 studies for full reading, after identification of the full studies, resulting in 8 studies that make up this review. Conclusion: Video-based tasks with systematized interventions had the most significant effects on attention and working memory variables. Other outcomes have been reported in static and dynamic balance. Virtual reality-based tasks improved memory selective processes and memory function perception

Modelagem de processos e decisões: um estudo aplicado ao processo de tratamento medicamentoso de oncologia

This research proposes the study of a health area process through the modeling of processes and decisions. The modeling of processes and decisions applied to the health area can help in several factors, including the verification of control and traceability points, which reduce the risks to the patient's health and increase the quality of the service provided. The main objective of this research is to describe the logic of an oncology drug treatment process, from end to end, in order to indicate its control points and describe the logic of the decisions made in critical points of this process. The research also presents some specific objectives that are detailed in the introduction. In the theoretical foundation, the terms used during the research are clarified, in order to research the themes related to the modeling of processes and decisions, as well as their relationship in the health area. For the scientific conduct of this research, the modeling method will be used. This paper presents the creation of business process and decision models related to drug treatment in oncology through the use of Business Process Model and Notation and Decision Model and Notation. In addition, it aims to highlight the control points mapped in the process and address them using the 5W1H tool. The model created in BPMN will be exposed to the application of some comprehensibility guidelines, evaluating which ones were followed by the model and the work that was done to adapt the model to comply with others. It is intended to apply a method of verification and validation of diagrammatic models which is still under development and will be detailed during this research. Finally, this work concluded that the BPMN notation was effective in mapping the cancer treatment process, demonstrating the already established control points and the risks at certain points in the process. Also, the application of the DMN notation and its relationship with the BPMN notation was discussed, which showed the difficulty in applying it in processes where the decision has a high level of personalization.Esta pesquisa propôs o estudo de um processo da área da saúde por meio da modelagem de processos e de decisões. A modelagem de processos e de decisões aplicada à área da saúde pode auxiliar em diversos fatores, incluindo a verificação de pontos de controle e de rastreabilidade, os quais diminuem os riscos para a saúde do paciente e aumenta a qualidade do serviço prestado. O objetivo principal desta pesquisa foi descrever a lógica de um processo de tratamento medicamentoso de oncologia, de ponta a ponta, de modo a indicar os seus pontos de controles e descrever a lógica das decisões realizadas em pontos críticos deste processo. A pesquisa também apresentou alguns objetivos específicos que são detalhados na introdução. Na fundamentação teórica, os termos utilizados durante a pesquisa foram esclarecidos, de modo que se pesquisou os temas relacionados à modelagem de processos e de decisões, assim como a associação na área da saúde. Para a condução científica desta pesquisa, foi utilizado o método de modelagem. Este trabalho apresentou a criação dos modelos de processo de negócio e de decisões relacionados ao tratamento medicamentoso de oncologia por meio da utilização das notações Business Process Model and Notation e Decision Model and Notation. Além disso, visou destacar os controles mapeados no processo e abordá-los utilizando a ferramenta 5W1H. O modelo criado em BPMN foi exposto à aplicação de algumas diretrizes de compreensibilidade, avaliando quais delas foram seguidas pelo modelo e o trabalho que foi realizado para adaptar o modelo ao cumprimento de outras. Foi aplicado um método de verificação e validação de modelos diagramáticos o qual ainda se encontra em desenvolvimento e será detalhado durante esta pesquisa. Por fim, este trabalho concluiu que a notação BPMN foi eficaz ao mapear o processo de tratamento oncológico, demonstrando os controles já estabelecidos e os riscos detectados no processo. Ainda, foi discutida a aplicação da notação DMN e a sua relação com a notação BPMN, a qual mostrou dificuldade em ser aplicada em processos com decisões altamente personalizadas