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Roux-en-Y gastric by-pass (RYGB) is one of the most effective bariatric procedures, but the rate of weight regain (WR) can reach 63% after the second year. Enlargement of the gastrojejunal anastomosis is one of the reported causes. A newly CE-marked flexible endoscopic system, Bariatric Anastomotic Reduction System (BARS) (Ovesco Endoscopy, Tuebingen, Germany), derivative of the well-established endoscopic over-the-scope-clip (OTSC) clipping system, has been recently developed. It was tested in pre-clinical and preliminary clinical use for feasibility and effectiveness in bariatric anastomotic reduction.Using a single-channel endoscope with external supplemental working channel, the BARS device captures the two limbs of the anastomosis, reducing its size, thus slowing food passage. After preclinical assessment, six patients with at least a 15% WR and the presence of an enlarged gastrojejunostomy20 mm were enrolled. The mean patient age was 49 years (range 24-67). Average interval between gastric bypass and BARS procedure: 8 years (4-13).All procedures were safely performed without complications. Mean procedure time: 52 min (37 - 75). Preliminary results: mean weight loss 6 kg (4-9) at a 3-month FU.BARS could be a promising endoscopic system in case of WR after gastric bypass due to enlargement of the anastomosis.

Multi-loop matter-wave interferometers are essential in quantum sensing to measure the derivatives of physical quantities in time or space. Because multi-loop interferometers require multiple reflections, imperfections of the matter-wave mirrors create spurious paths that scramble the signal of interest. Here we demonstrate a method of adjustable momentum transfer that prevents the recombination of the spurious paths in a double-loop atom interferometer aimed at measuring rotation rates. We experimentally study the recombination condition of the spurious matter waves, which is quantitatively supported by a model accounting for the coherence properties of the atomic source. We finally demonstrate the effectiveness of the method in building a cold-atom gyroscope with a single-shot acceleration sensitivity suppressed by a factor of at least 50. Our study will impact the design of multi-loop atom interferometers that measure a single inertial quantity., Comment: 4 pages of main text, 33 references, 6 pages of Supplemental Material

This presentation will review some of the latest state-of-the-art developments in cold-atom inertial sensors developped at the SYRTE laboratory in Paris.

OBJECTIVE Evaluate if bariatric surgery can improve hypertension (HPT) control leading to both reduction of blood pressure values and antihypertensive therapy withdrawal. METHODS Eight-hundred and sixty-four consecutive patients who referred to our hospital, from March 2001 to February 2011, because of morbid obesity were initially enrolled in this retrospective study. To obtain two comparable groups, propensity-matching was applied. Finally, the study included 444 (51% out of initial 864 patients), 222 on diet (group D) and 222 patients undergoing surgery (group S). RESULTS In group D, sistolic blook pressure (SBP) showed a significant increase (135 ± 14 vs 138 ± 11 mmHg; P = 0.006); conversely in group S, SBP decreased (130 ± 14 vs 124 ± 9 mmHg; P = 0.001). In group D, diastolic blood pressure (DBP) showed a significant increase (80 ± 6 vs 82 ± 6 mmHg; P = 0.004); conversely in group S, DBP decreased (81 ± 9 vs 79 ± 8 mmHg; P = 0.015). Among 136 patients with HPT, 73 (53%) withdrew antihypertensive therapy: significantly more in group S (55/63, 87%) than in group D (17/56, 23%), P

We present a cold atom gyroscope based on the Sagnac effect for matter-wave with very large area of 11 cm2 with record sensitivity and preliminary study of the scaling factor.

This thesis describes the implementation of new atom interferometry techniques to improve the stability and accuracy of a cold-atom gyroscope located at the SYRTE laboratory. Stimulated Raman transitions are used to split and recombine the atomic waves. A sequence of four light pulses generates an interferometer with a Sagnac area of 11 cm2. I present the implementation of an interleaved interrogation scheme, where three atomic clouds are interrogated simultaneously in an atom interferometer featuring a sampling rate of 3.75 Hz and an interrogation time of 801 ms. With this scheme we demonstrate a short-term sensitivity of 30 nrad·s-1·Hz-1/2. We then present measurements of dynamic rotation rates in a so far unexplored range for a cold atom sensor. An important bias of the sensor originates from a coupling between a relative misalignment of the mirrors which retro-reflect the Raman beams and the trajectory of the atom. A technique is introduced to reduce this bias at the level of 3 nrad·s-1 and to achieve a long-term stability of 0.3 nrad·s-1 which represents the state of the art for atomic gyroscopes. The manuscript then describes the first characterization of the scale factor of the gyroscope using different techniques. In particular, the implementation of a rotation stage below the sensor enables us to vary the projection of the Erath rotation rate vector onto the interferometer area and therefore to modulate the rotation phase shift. The implementation of the techniques presented in this thesis pave paving the way to a test of the Sagnac effect for matter waves with a relative accuracy level below 100 parts per million.; Cette thèse décrit la mise en œuvre de nouvelles techniques d'interférométrie atomique améliorant la stabilité et l’exactitude d'un gyromètre à atomes froids situé au laboratoire SYRTE. Des transitions Raman stimulées permettent de séparer et recombiner les ondes atomiques. Une séquence de quatre impulsions lumineuses génère un interféromètre avec une aire Sagnac de 11 cm2. Je présente la mise en œuvre d'un schéma d'interrogation entrelacé dans un interféromètre dont le temps d'interrogation est de 801 ms, dans lequel trois nuages atomiques sont interrogés simultanément résultant en une cadence de mesure de 3,75 Hz. Avec ce schéma, nous démontrons une sensibilité de 30 nrad/s/sqrt(Hz). Nous présentons ensuite des mesures de rotation dynamiques dans une plage jusqu'ici inexplorée pour un capteur à atomes froids. Un biais important du capteur provient d'un couplage entre un désalignement relatif des miroirs rétroréfléchissant les faisceaux Raman et la trajectoire de l'atome. Une technique est introduite pour réduire ce biais au niveau de 3 nrad/s et atteindre une stabilité à long terme de 0,3 nrad/s qui représente l'état de l'art des gyromètres atomiques. Le manuscrit décrit ensuite la première caractérisation du facteur d'échelle du gyromètre à l'aide de différentes techniques. En particulier, la mise en place d’une plateforme de rotation sous le capteur permet de faire varier la projection du vecteur rotation de la Terre sur l'interféromètre et donc de moduler le déphasage de rotation. Les techniques présentées dans cette thèse ouvrent la voie à un test de l'effet Sagnac pour les ondes de matière avec une précision relative inférieure à 100 parties par million.

This thesis describes the implementation of new atom interferometry techniques to improve the stability and accuracy of a cold-atom gyroscope located at the SYRTE laboratory. Stimulated Raman transitions are used to split and recombine the atomic waves. A sequence of four light pulses generates an interferometer with a Sagnac area of 11 cm2. I present the implementation of an interleaved interrogation scheme, where three atomic clouds are interrogated simultaneously in an atom interferometer featuring a sampling rate of 3.75 Hz and an interrogation time of 801 ms. With this scheme we demonstrate a short-term sensitivity of 30 nrad·s-1·Hz-1/2. We then present measurements of dynamic rotation rates in a so far unexplored range for a cold atom sensor. An important bias of the sensor originates from a coupling between a relative misalignment of the mirrors which retro-reflect the Raman beams and the trajectory of the atom. A technique is introduced to reduce this bias at the level of 3 nrad·s-1 and to achieve a long-term stability of 0.3 nrad·s-1 which represents the state of the art for atomic gyroscopes. The manuscript then describes the first characterization of the scale factor of the gyroscope using different techniques. In particular, the implementation of a rotation stage below the sensor enables us to vary the projection of the Erath rotation rate vector onto the interferometer area and therefore to modulate the rotation phase shift. The implementation of the techniques presented in this thesis pave paving the way to a test of the Sagnac effect for matter waves with a relative accuracy level below 100 parts per million., Cette thèse décrit la mise en œuvre de nouvelles techniques d'interférométrie atomique améliorant la stabilité et l’exactitude d'un gyromètre à atomes froids situé au laboratoire SYRTE. Des transitions Raman stimulées permettent de séparer et recombiner les ondes atomiques. Une séquence de quatre impulsions lumineuses génère un interféromètre avec une aire Sagnac de 11 cm2. Je présente la mise en œuvre d'un schéma d'interrogation entrelacé dans un interféromètre dont le temps d'interrogation est de 801 ms, dans lequel trois nuages atomiques sont interrogés simultanément résultant en une cadence de mesure de 3,75 Hz. Avec ce schéma, nous démontrons une sensibilité de 30 nrad/s/sqrt(Hz). Nous présentons ensuite des mesures de rotation dynamiques dans une plage jusqu'ici inexplorée pour un capteur à atomes froids. Un biais important du capteur provient d'un couplage entre un désalignement relatif des miroirs rétroréfléchissant les faisceaux Raman et la trajectoire de l'atome. Une technique est introduite pour réduire ce biais au niveau de 3 nrad/s et atteindre une stabilité à long terme de 0,3 nrad/s qui représente l'état de l'art des gyromètres atomiques. Le manuscrit décrit ensuite la première caractérisation du facteur d'échelle du gyromètre à l'aide de différentes techniques. En particulier, la mise en place d’une plateforme de rotation sous le capteur permet de faire varier la projection du vecteur rotation de la Terre sur l'interféromètre et donc de moduler le déphasage de rotation. Les techniques présentées dans cette thèse ouvrent la voie à un test de l'effet Sagnac pour les ondes de matière avec une précision relative inférieure à 100 parties par million.

Cold-atom interferometers commonly face systematic effects originating from the coupling between the trajectory of the atomic wave packet and the wave front of the laser beams driving the interferometer. Detrimental for the accuracy and the stability of such inertial sensors, these systematics are particularly enhanced in architectures based on spatially separated laser beams. Here we analyze the effect of a coupling between the relative alignment of two separated laser beams and the trajectory of the atomic wave packet in a four-light-pulse cold-atom gyroscope operated in fountain configuration. We present a method to align the two laser beams at the $0.2 \ \mu$rad level and to determine the optimal mean velocity of the atomic wave packet with an accuracy of $0.2\ \textrm{mm}\cdot\textrm{s}^{-1}$. Such fine tuning constrains the associated gyroscope bias to a level of $1\times 10^{-10}~\textrm{rad}\cdot\textrm{s}^{-1}$. In addition, we reveal this coupling using the point-source interferometry technique by analyzing single-shot time-of-flight fluorescence traces, which allows us to measure large angular misalignments between the interrogation beams. The alignment method which we present here can be employed in other sensor configurations and is particularly relevant to emerging gravitational wave detector concepts based on cold-atom interferometry., Comment: 10 pages including appendices, 23 references

Interleaved atom interferometry brings high sensitivity and temporal resolution to cold-atom inertial sensors., Cold-atom inertial sensors target several applications in navigation, geoscience, and tests of fundamental physics. Achieving high sampling rates and high inertial sensitivities, obtained with long interrogation times, represents a challenge for these applications. We report on the interleaved operation of a cold-atom gyroscope, where three atomic clouds are interrogated simultaneously in an atom interferometer featuring a sampling rate of 3.75 Hz and an interrogation time of 801 ms. Interleaving improves the inertial sensitivity by efficiently averaging vibration noise and allows us to perform dynamic rotation measurements in a so far unexplored range. We demonstrate a stability of 3 × 10−10 rad s−1 , which competes with the best stability levels obtained with fiber-optic gyroscopes. Our work validates interleaving as a key concept for future atom-interferometry sensors probing time-varying signals, as in on-board navigation and gravity gradiometry, searches for dark matter, or gravitational wave detection.

We present a matter-wave gyroscope with 11 cm2Sagnac area operating without dead times and at a sampling frequency of 3.75 Hz. This is achieved by interleaving the atom laser-cooling step and the interrogation of the atoms. We demonstrate a record short term sensitivity of 30 nrad.s-1. Hz-1/2, which allows us to characterize and stabilize systematic effects below $3\times 10^{-10}\mathbf{rad}.\mathbf{s}^{-1}$ after 15 000 seconds of integration time. Such level of stability competes with best long term stabilities obtained with fiber-optics gyroscopes, and paves the way for applications of cold-atom sensors in inertial navigation or geoscience.

We study theoretically and experimentally the influence of temporally shaping the light pulses in an atom interferometer, with a focus on the phase response of the interferometer. We show that smooth light pulse shapes allow rejecting high frequency phase fluctuations (above the Rabi frequency) and thus relax the requirements on the phase noise or frequency noise of the interrogation lasers driving the interferometer. The light pulse shape is also shown to modify the scale factor of the interferometer, which has to be taken into account in the evaluation of its accuracy budget. We discuss the trade-offs to operate when choosing a particular pulse shape, by taking into account phase noise rejection, velocity selectivity, and applicability to large momentum transfer atom interferometry., accepted in New Journal of Physics

The uniformity of the intensity and phase of laser beams is crucial to high-performance atom interferometers. Inhomogeneities in the laser intensity profile cause contrast reductions and systematic effects in interferometers operated with atom sources at micro-Kelvin temperatures, and detrimental diffraction phase shifts in interferometers using large momentum transfer beam splitters. We report on the implementation of a so-called top-hat laser beam in a long-interrogation-time cold-atom interferometer to overcome the issue of the inhomogeneous laser intensity encountered when using Gaussian laser beams. We characterize the intensity and relative phase profiles of the top-hat beam and demonstrate its gain in atom-optics efficiency over a Gaussian beam, in agreement with numerical simulations. We discuss the application of top-hat beams to improve the performance of different architectures of atom interferometers., 4 pages plus references and Supplemental Material

Our cold-atom gyroscope is based on a four-pulse configuration with a very large Sagnac area. Its short-term stability is limited by aliasing effects of the inertial forces (acceleration and rotation). We will show how continuous measurements and real-time compensation of the vibration during the interferometer sequence overcome this limit.

International audience

International audience

International audience

The best possible precision is one of the key figures in metrology, but this is established by the exact response of the detection apparatus, which is often unknown. There exist techniques for detector characterization that have been introduced in the context of quantum technologies but apply as well for ordinary classical coherence; these techniques, though, rely on intense data processing. Here, we show that one can make use of the simpler approach of data fitting patterns in order to obtain an estimate of the Cramer-Rao bound allowed by an unknown detector, and we present applications in polarimetry. Further, we show how this formalism provides a useful calculation tool in an estimation problem involving a continuous-variable quantum state, i.e., a quantum harmonic oscillator.