6-axis inertial sensor using cold-atom interferometry

We have developed an atom interferometer providing a full inertial base. This device uses two counter-propagating cold-atom clouds that are launched in strongly curved parabolic trajectories. Three single Raman beam pairs, pulsed in time, are successively applied in three orthogonal directions leading to the measurement of the three axis of rotation and acceleration. In this purpose, we introduce a new atom gyroscope using a butterfly geometry. We discuss the present sensitivity and the possible improvements.Comment: submitted to PR

Influence of optical aberrations in an atomic gyroscope

In atom interferometry based on light-induced diffraction, the optical aberrations of the laser beam splitters are a dominant source of noise and systematic effect. In an atomic gyroscope, this effect is dramatically reduced by the use of two atomic sources. But it remains critical while coupled to fluctuations of atomic trajectories, and appears as a main source of noise to the long term stability. Therefore we measure these contributions in our setup, using cold Cesium atoms and stimulated Raman transitions

Development of a strontium optical lattice clock for the SOC mission on the ISS

Ultra-precise optical clocks in space will allow new studies in fundamental physics and astronomy. Within an European Space Agency (ESA) program, the Space Optical Clocks (SOC) project aims to install and to operate an optical lattice clock on the International Space Station (ISS) towards the end of this decade. It would be a natural follow-on to the ACES mission, improving its performance by at least one order of magnitude. The payload is planned to include an optical lattice clock, as well as a frequency comb, a microwave link, and an optical link for comparisons of the ISS clock with ground clocks located in several countries and continents. Within the EU-FP7-SPACE-2010-1 project no. 263500, during the years 2011-2015 a compact, modular and robust strontium lattice optical clock demonstrator has been developed. Goal performance is a fractional frequency instability below 1x10^{-15}, tau^{-1/2} and a fractional inaccuracy below 5x10^{-17}. Here we describe the current status of the apparatus' development, including the laser subsystems. Robust preparation of cold {88}^Sr atoms in a second stage magneto-optical trap (MOT) is achieved.Comment: 27 Pages, 15 figures, Comptes Rendus Physique 201

Integrative analysis of genomic, functional and protein interaction data predicts long-range enhancer-target gene interactions

Multicellular organismal development is controlled by a complex network of transcription factors, promoters and enhancers. Although reliable computational and experimental methods exist for enhancer detection, prediction of their target genes remains a major challenge. On the basis of available literature and ChIP-seq and ChIP-chip data for enhanceosome factor p300 and the transcriptional regulator Gli3, we found that genomic proximity and conserved synteny predict target genes with a relatively low recall of 12–27% within 2 Mb intervals centered at the enhancers. Here, we show that functional similarities between enhancer binding proteins and their transcriptional targets and proximity in the protein–protein interactome improve prediction of target genes. We used all four features to train random forest classifiers that predict target genes with a recall of 58% in 2 Mb intervals that may contain dozens of genes, representing a better than two-fold improvement over the performance of prediction based on single features alone. Genome-wide ChIP data is still relatively poorly understood, and it remains difficult to assign biological significance to binding events. Our study represents a first step in integrating various genomic features in order to elucidate the genomic network of long-range regulatory interactions

Benefits and challenges of high sensitivity atom interferometers in optical cavities

International audienc

Benefits and challenges of high sensitivity atom interferometers in optical cavities

International audienc

Horloge à refroidissement d'atomes dans un champ speckle 3D en cellule

Nous présentons l'étude du refroidissement laser réalisé dans une cavité micro-onde polie au niveau optique. Le champ de speckle présent dans la cellule permet la réalisation de l'effet Sisyphe, responsable des faibles températures mesurées au sein de la mélasse optique. Pour des temps de capture de l'ordre de la seconde, on accumule à partir d'une vapeur thermique, environ 10$^{8}$ atomes froids de césium dans un nuage de 4 mm de diamètre à une température de 3 $\mu$K

Benefits and challenges of high sensitivity atom interferometers in optical cavities

International audienc

Piégeage cohérent de population sur des atomes froids

Dans le cadre de futures horloges atomiques compactes destinées à la navigation spatiale, il est possible de remplacer l'interrogation micro-onde d'une horloge atomique classique par une interrogation optique à l'aide de faisceaux Raman et d'asservir un oscillateur à quartz sur la réponse atomique crée par le phénomène de piégeage cohérent de population (CPT en anglais pour Coherent Population Trapping)