[Show abstract][Hide abstract] ABSTRACT: We present here an analysis of the influence onto the phase of a Raman atom
gravimeter of the frequency dependence of the Raman laser light shifts. We show
in particular that the change in the Raman light shift due to the frequency
chirp used to compensate gravity and ensure the resonance of the Raman pulses
is enough to bias the gravity measurement by a fraction of \muGal. More
important, this effect does not compensate when averaging over the two
directions of the direction of the Raman wavevector and thus constitutes a
limit to the rejection efficiency of the latter technique. This study
highlights the bene?fit of chirping the two Raman lasers in opposite
[Show abstract][Hide abstract] ABSTRACT: After separate developments of the different elements with continuous characterizations and
improvements, the LNE watt balance has been assembled. This paper describes the system in
detail and gives its first measurements of the Planck’s constant h. The value determined in air
is h = 6.626 068 8(20) × 10−34 Js which differs in relative terms by −0.05 × 10−7 from the
h90 value and by −1.1 × 10−7 from that of the 2010 CODATA adjustment of h. The relative
standard uncertainty associated is 3.1 × 10−7.
[Show abstract][Hide abstract] ABSTRACT: This paper describes the progress of a joint research project aimed at developing and demonstrating the technologies, based both on the watt balance experiment and the counting of 28Si atoms, necessary to realize the kilogram on the basis of an agreed conventional value of the Planck constant.
Precision Electromagnetic Measurements, Rio de Janeiro; 08/2014
[Show abstract][Hide abstract] ABSTRACT: The European Metrology Research Programme (EMRP) funds research to address the discrepancy between the values of the Planck and Avogadro constants measured via the watt balance experiments and by the counting of 28Si atoms. The strategy will be to strain the procedures, models, and apparatuses up to their limit by repeating the measurements with accuracies stricter than those achievable by today's technologies
[Show abstract][Hide abstract] ABSTRACT: This paper presents the current status and future prospects of the Space Atom Interferometer project (SAI), funded by the European Space Agency. Atom interferometry provides extremely sensitive and accurate tools for the measurement of inertial forces. Operation of atom interferometers in microgravity is expected to enhance the performance of such sensors. Main goal of SAI is to demonstrate the possibility of placing atom interferometers in space. The resulting drop-tower compatible atom interferometry acceleration sensor prototype is described. Expected performance limits and potential scientific applications in a micro-gravity environment are also discussed.
Journal of Physics Conference Series 12/2011; 327(1):012050. DOI:10.1088/1742-6596/327/1/012050
[Show abstract][Hide abstract] ABSTRACT: We present a numerical method, based on a FEM simulation, for the
determination of the gravitational field generated by massive objects, whatever
geometry and space mass density they have. The method was applied for the
determination of the self gravity effect of an absolute cold atom gravimeter
which aims at a relative uncertainty of 10-9. The deduced bias, calculated with
a perturbative treatment, is finally presented. The perturbation reaches (1.3
\pm 0.1) \times 10-9 of the Earth's gravitational field.
[Show abstract][Hide abstract] ABSTRACT: We present iSense, a recently initiated FET project aiming to use Information and Communication Technologies (ICT) to develop a platform for portable quantum sensors based on cold atoms. A prototype of backpack-size highprecision force sensor will be built to demonstrate the concept. (C) Selection and peer-review under responsibility of FET11 conference organizers and published by Elsevier B.V.
2nd European Future Technologies Conference and Exhibition (FET); 01/2011
[Show abstract][Hide abstract] ABSTRACT: The International Bureau of Weights and Measures (BIPM) was set up by the Metre Convention and has its headquarters near Paris, France. It is financed jointly by its Member States and operates under the exclusive supervision of the CIPM. Its mandate is to provide the basis for a single, coherent system of measurements throughout the world, traceable to the International System of Units (SI). This task takes many forms, from direct dissemination of units (as in the case of mass and time) to coordination through international comparisons of national measurement standards (as in electricity and ionizing radiation). The BIPM has an international staff of over 70 and its status vis-à-vis the French Government is similar to that of other intergovernmental organizations based in Paris.
[Show abstract][Hide abstract] ABSTRACT: The e-MASS joint research project (JRP) supported by EURAMET gathers several European metrology institutes in the aim to improve existing watt balances and to contribute to a new definition of the mass unit. This paper describes the main technical tasks developed in the framework of the project.
[Show abstract][Hide abstract] ABSTRACT: We use atom interferometry to perform an absolute measurement of the gravitational acceleration g.
The sensitivity of the interferometer is predominantly limited by vibration noise, even when drastically reduced by using
a passive isolation platform. We present here an original correction scheme of the residual vibration induced interferometer
phase fluctuations, based on the use of a low noise seismometer. In the best conditions, our instrument reaches an excellent
sensitivity of 1.4 × 10−
g at 1 s, despite operating in an urban environment. But the method presented here allows reaching good performances even when
operating without any vibration isolation. The sensitivity of our instrument at night is then as low as 5.5 × 10−
g at 1 s.
[Show abstract][Hide abstract] ABSTRACT: Two extended cavity laser diodes are phase-locked, thanks to an intra-cavity electro-optical modulator. The phase-locked loop bandwidth is on the order of 10 MHz, which is about twice larger than when the feedback correction is applied on the laser current. The phase noise reaches −120 dBrad2/Hz at 10 kHz. This new scheme reduces the residual laser phase noise, which constitutes one of the dominant contributions in the sensitivity limit of atom interferometers using two-photon transitions.
[Show abstract][Hide abstract] ABSTRACT: This paper describes the main progress on the LNE watt balance project since 2004. Development of different parts and structure of the watt balance including starting their assembly are presented.
[Show abstract][Hide abstract] ABSTRACT: We present here an analysis of the sensitivity of a time-domain atomic interferometer to the phase noise of the lasers used to manipulate the atomic wave packets. The sensitivity function is calculated in the case of a three-pulse Mach-Zehnder interferometer, which is the configuration of the two inertial sensors we are building at the Laboratoire National de Metrologie et d'Essais-Systeme de References Temps-Espace. We successfully compare this calculation to experimental measurements. The sensitivity of the interferometer is limited by the phase noise of the lasers as well as by residual vibrations. We evaluate the performance that could be obtained with state-of-the-art quartz oscillators, as well as the impact of the residual phase noise of the phase-locked loop. Requirements on the level of vibrations are derived from the same formalism.
IEEE Transactions on Instrumentation and Measurement 07/2008; 57(6-57):1141 - 1148. DOI:10.1109/TIM.2007.915148 · 1.79 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Summary form only given. A collaboration between European research groups is developing novel atomic inertial quantum sensors based on matter-wave optics and Raman interferometry. For this purpose we are implementing a gravimeter and a gyroscope using ultra cold atoms as test masses. Inertial quantum sensors could represent a new tool for the precise detection of faint forces and tiny rotations. According to the principle of these sensors, the measured physical quantity will be converted into a frequency, which can be measured with highest accuracy. The items of atom interferometry will range from fundamental physical tests to many practical applications such as: local gravity measurements, allowing a precise underground mapping, and space navigation. In this contest the main goal is to realize modular and portable systems.
Lasers and Electro-Optics, 2007 and the International Quantum Electronics Conference. CLEOE-IQEC 2007. European Conference on; 07/2007
[Show abstract][Hide abstract] ABSTRACT: In atom interferometers based on two photon transitions, the delay induced by the difference of the laser beams paths makes the interferometer sensitive to the fluctuations of the frequency of the lasers. We first study, in the general case, how the laser frequency noise affects the performance of the interferometer measurement. Our calculations are compared with the measurements performed on our cold atom gravimeter based on stimulated Raman transitions. We finally extend this study to the case of cold atom gradiometers. Comment: 17 pages, 6 figures
The European Physical Journal D 01/2007; 44(3). DOI:10.1140/epjd/e2007-00218-2 · 1.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Dans le cadre du projet français de Balance du Watt, visant à redéfinir l'unité de masse du système international , un gravimètre atomique est en cours de mise au point à l'Observatoire de Paris. La mesure de g est basée sur les interférences entre ondes de matières d'atomes froids de 87 Rb. Les premières franges d'interférences ont été obtenues cette année, et la stabilité atteinte est de 7.10-8 g/surd Hz.
Journal de Physique IV (Proceedings) 10/2006; 135(1):213-214. DOI:10.1051/jp4:2006135062 · 0.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We describe an optical bench in which we lock the relative frequencies or phases of a set of three lasers in order to use them in a cold atom interferometry experiment. As a new feature, the same two lasers serve alternately to cool atoms and to realize the atomic interferometer. This requires a fast change of the optical frequencies over a few GHz. The number of required independent laser sources is then only three, which enables the construction of the whole laser system on a single transportable optical bench. Recent results obtained with this optical setup are also presented.
Applied Physics B 09/2006; 84(4). DOI:10.1007/s00340-006-2266-2 · 1.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Over the last few years the number of high accuracy (uncertainties in the low 10-15 or less) primary frequency standards contributing to TAI has increased significantly from only two over the period 2000 - 2002 to seven over the period 2002 - 2005. As a consequence the number of individual measurements of TAI frequency by such standards over the period 1999 to 2005 is >; 60 and increasing rapidly. Additionally, several other atomic transition frequencies (Rb, Yb+, Hg+, Sr+,...) have been repeatedly measured over the same period with comparable accuracies. The resulting overall set of data is now sufficiently large to be able to obtain meaningful statistics for the complete data set and, in some cases, for the contributions from individual standards. We show the ensemble of the data available to the BIPM at the time of the conference together with the results of some basic statistical analysis. In particular, we investigate the impact of these standards on the overall uncertainty of the realisation of the SI second via TAI, and the performance of some individual standards. Our results indicate that while there is good self coherence of most studied standards (especially for recent data) there seems to be significant disagreement between individual standards. We briefly discuss some potential sources of that disagreement (time transfer noise, uncertainties of the standards, instability of the reference timescale, etc...). We hope that, in the long term, this ongoing study will allow a better characterisation of the ensemble of standards and their impact on TAI.
Frequency and Time Forum (EFTF), 2006 20th European; 01/2006