Double diffraction in an atomic gravimeter

We demonstrate the realization of a new scheme for cold atom gravimetry based on the use of double diffraction beamsplitters recently demonstrated in \cite{Leveque}, where the use of two retro-reflected Raman beams allows symmetric diffraction in $\pm \hbar k_{eff}$ momenta. Though in principle restricted to the case of zero Doppler shift, for which the two pairs of Raman beams are simultaneously resonant, we demonstrate that such diffraction pulses can remain efficient on atoms with non zero velocity, such as in a gravimeter, when modulating the frequency of one of the two Raman laser sources. We use such pulses to realize an interferometer insensitive to laser phase noise and some of the dominant systematics. This reduces the technical requirements and would allow the realization of a simple atomic gravimeter. We demonstrate a sensitivity of $1.2\times10^{-7}g$ per shot

A cold atom pyramidal gravimeter with a single laser beam

International audienceWe demonstrate a scheme for realizing a compact cold atom gravimeter. The use of a hollow pyramidal configuration allows to achieve all functions: trapping, interferometer and detection with a unique laser beam leading to a drastic reduction in complexity and volume. In particular, we demonstrate a relative sensitivity to acceleration of gravity (g) of 1.7 × 10-7 at one second, with a moderate laser power of 50 mW. This simple geometry combined to such a high sensitivity opens wide perspectives for practical applications (P. Bouyer and A. Landragin, patent n° FR2009/000252, 2009)

Operating an atom interferometer beyond its linear range

In this paper, we show that an atom interferometer inertial sensor, when associated to the auxiliary measurement of external vibrations, can be operated beyond its linear range and still keep a high acceleration sensitivity. We propose and compare two measurement procedures (fringe fitting and nonlinear lock) that can be used to extract the mean phase of the interferometer when the interferometer phase fluctuations exceed $2\pi$. Despite operating in the urban environment of inner Paris without any vibration isolation, the use of a low noise seismometer for the measurement of ground vibrations allows our atom gravimeter to reach at night a sensitivity as good as $5.5\times10^{-8}$g at 1 s. Robustness of the measurement to large vibration noise is also demonstrated by the ability of our gravimeter to operate during an earthquake with excellent sensitivity. Our high repetition rate allows for recovering the true low frequency seismic vibrations, ensuring proper averaging. Such techniques open new perspectives for applications in other fields, such as navigation and geophysics.Comment: 20 pages, 8 figure

Single strontium Rydberg ion confined in a Paul trap

Trapped Rydberg ions are a promising new system for quantum information processing. They have the potential to join the precise quantum operations of trapped ions and the strong, long-range interactions between Rydberg atoms. Combining the two systems is not at all straightforward. Rydberg atoms are severely affected by electric fields which may cause Stark shifts and field ionization, while electric fields are used to trap ions. Thus, a thorough understanding of the physical properties of Rydberg ions due to the trapping electric fields is essential for future applications. Here we report the observation of two fundamental trap effects. First, we investigate the interaction of the Rydberg electron with the trapping electric quadrupole fields which leads to Floquet sidebands in the excitation spectra. Second, we report on the modified trapping potential in the Rydberg state compared to the ground state which results from the strong polarizability of the Rydberg ion. By controlling both effects we observe resonance lines close to their natural linewidth demonstrating an unprecedented level of control of this novel quantum platform

Single strontium Rydberg ion confined in a Paul trap

Trapped Rydberg ions are a promising new system for quantum information processing. They have the potential to join the precise quantum operations of trapped ions and the strong, long-range interactions between Rydberg atoms. Combining the two systems is not at all straightforward. Rydberg atoms are severely affected by electric fields which may cause Stark shifts and field ionization, while electric fields are used to trap ions. Thus, a thorough understanding of the physical properties of Rydberg ions due to the trapping electric fields is essential for future applications. Here we report the observation of two fundamental trap effects. First, we investigate the interaction of the Rydberg electron with the trapping electric quadrupole fields which leads to Floquet sidebands in the excitation spectra. Second, we report on the modified trapping potential in the Rydberg state compared to the ground state which results from the strong polarizability of the Rydberg ion. By controlling both effects we observe resonance lines close to their natural linewidth demonstrating an unprecedented level of control of this novel quantum platform

Gravimétrie atomique, amélioration de l'exactitude et nouvelles géométries

The goal of the absolute gravimeter is to measure the gravitational accelration with a relative accuracy of 10-9 for the metrological "watt balance" project. During my thesis, we developped a new vaccum chamber, which allowed us to evaluate the limiting systematic errors. The gravimeter was made transportable and was installed close to the LNE watt balance. The gravimeter uses atom interferometry, where a cold cloud of 87Rb atoms in free fall is manipulated thanks to two-photon transitions. We reduced the measurement uncertainty below the goal, except for laser wavefront aberation effects. This is currently under investigations and we aim for perfect control of the atomic trajectories. During the year 2010, our atomic gravimeter participated in international "Key" comparisons. The results we obtained are in agreement with other gravimeters, but we observed some fluctuations in the differences with other gravimeters, caused by variations of the wavefront aberration effects. In parallel, we developed three new methods of atom interferometry measurement. The first method uses a three-point algorithm which makes the measurement robust from vibrations. The second consists in diffracting atoms simultaneously by the four fields present in the chamber, in order to double the area of the interferometer, and thus increases its intrinsic sensitivity. Last, we designed and characterized a hollow pyramid, which allows the differents lasers to be replaced by a single laser beam, in order to create a compact transportable atomic gravimeter.L'objectif du gravimètre absolu est de déterminer la valeur de l'accélération de pesanteur g avec une incertitude relative de 10-9 pour le projet métrologique de "balance du watt". Nous avons développé pendant ma thèse une nouvelle enceinte à vide permettant l'évaluation des effets systématiques limitant. Le gravimètre a été rendu transportable et placé à côté de la balance du LNE. Le gravimètre repose sur des techniques d'interférométrie atomique, où un nuage d'atomes froids de 87Rb en chute libre est manipulé au moyen de transitions à deux photons. Nous avons réduit l'incertitude sur l'ensemble des biais au-dessous de l'objectif, excepté l'effet des aberrations du front d'onde des faisceaux lasers. Il est actuellement l'objet de nos investigations et nous cherchons à contrôler le mieux possible la trajectoire des atomes. Au cours de l'année 2010, notre gravimètre atomique a participé à des comparaisons "clefs" internationales. Les valeurs de g obtenues sont en accord, mais nous relevons des fluctuations de l'écart avec les autres gravimètres, liées en partie aux variations de l'effet d'aberration. Nous avons développé en parallèle trois nouvelles techniques de mesures d'interférométrie atomique. La première utilise un algorithme à trois coups qui rend la mesure robuste aux vibrations. La seconde consiste à diffracter les atomes simultanément au moyen des quatre champs présents dans l'enceinte à vide afin de doubler l'aire de l'interféromètre et donc sa sensibilité intrinsèque. Enfin nous avons conçu et caractérisé une pyramide creuse, qui permet de substituer aux différents lasers un unique large faisceau, afin de créer un gravimètre atomique transportable compact

Gravimétrie atomique (amélioration de l'exactitude et nouvelles géométries)

L'objectif du gravimètre absolu est de déterminer la valeur de l'accélération de pesanteur g avec une incertitude relative de 10-9 pour le projet métrologique de "balance du watt". Nous avons développé pendant ma thèse une nouvelle enceinte à vide permettant l'évaluation des effets systématiques limitant. Le gravimètre a été rendu transportable et placé à côté de la balance du LNE. Le gravimètre repose sur des techniques d interférométrie atomique, où un nuage d atomes froids de 87Rb en chute libre est manipulé au moyen de transitions à deux photons. Nous avons réduit l'incertitude sur l'ensemble des biais au-dessous de l'objectif, excepté l effet des aberrations du front d'onde des faisceaux lasers. Il est actuellement l'objet de nos investigations et nous cherchons à contrôler le mieux possible la trajectoire des atomes. Au cours de l'année 2010, notre gravimètre atomique a participé à des comparaisons "clefs" internationales. Les valeurs de g obtenues sont en accord, mais nous relevons des fluctuations de l'écart avec les autres gravimètres, liées en partie aux variations de l'effet d aberration. Nous avons développé en parallèle trois nouvelles techniques de mesures d'interférométrie atomique. La première utilise un algorithme à trois coups qui rend la mesure robuste aux vibrations. La seconde consiste à diffracter les atomes simultanément au moyen des quatre champs présents dans l'enceinte à vide afin de doubler l aire de l interféromètre et donc sa sensibilité intrinsèque. Enfin nous avons conçu et caractérisé une pyramide creuse, qui permet de substituer aux différents lasers un unique large faisceau, afin de créer un gravimètre atomique transportable compact.PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Mounier Kuhn syndrome presenting with recurrent atelectasis

Objective and importance Mounier Kuhn syndrome is usually diagnosed in adulthood, and only a few cases have been described in childhood. Clinical presentation We present the case of a seven-year-old boy suffering from recurrent pneumonia and atelectasis. Intervention Previously performed chest X-rays showed bilateral hyperinflation and tracheobronchomegaly. Chest computed tomography (CT) confirmed the presence of distal enlargement of trachea and bronchi. Tracheobronchomegaly associated with recurrent respiratory tract infections is consistent with Mounier Kuhn syndrome. Pseudomonas aeruginosa was isolated from the sputum of the patient. He was then treated according to the guidelines for P. aeruginosa management in cystic fibrosis patients considering the similarities in clinical presentations and pathophysiology of both diseases. Antibiotic treatment resulted in a remarkable reduction of events of pulmonary exacerbation and hospitalizations. There are no specific guidelines for treatment options in case of pulmonary exacerbation of Mounier Kuhn syndrome. Case reports discussing the choice and efficiency of antibiotic treatment are random. Conclusion headings We share our experience of treating pulmonary exacerbation caused by P. aeruginosa in a patient with Mounier Kuhn syndrome suggesting a possible treatment option of pseudomonas infections in this syndrome.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Accuracy of a cold atom gravimeter

International audienc