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Field optical clocks and sensitivity to mass anomalies for geoscience applications / Guillaume Lion (2023)
Titre : Field optical clocks and sensitivity to mass anomalies for geoscience applications Type de document : Article/Communication Auteurs : Guillaume Lion , Auteur ; Gwendoline Pajot-Métivier , Auteur ; Kristel Chanard , Auteur ; Michel Diament , Auteur Editeur : Munich [Allemagne] : European Geosciences Union EGU Année de publication : 2023 Projets : ROYMAGE / Letargat, Rodolphe Conférence : EGU 2023, General Assembly 23/04/2023 28/04/2023 Vienne Autriche OA Abstracts only Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse de sensibilité
[Termes IGN] anomalie de pesanteur
[Termes IGN] chronométrie
[Termes IGN] horloge optiqueIndex. décimale : 30.60 Géodésie spatiale Résumé : (auteur) 350 years ago, the pendulum clock for astronomical observations was diverted to become an instrument for measuring gravity. The measurement of the parallax of Mars by Richer and Cassini from Cayenne and Paris showed that the period of a periodic oscillator depends on the gravity field. A link was thus established between the improvement of time measurement and the knowledge of the phenomena that govern it. Since then, the performance and nature of clocks have evolved considerably. Today, atomic clocks are used in various fields that are essential to modern society, such as the realisation of international atomic time (TAI), satellite navigation (GNSS), geodesy, the traceability of trading events, etc. In the framework of the french ANR ROYMAGE, we are interested in the contribution of a transportable optical field clock for geoscience applications by using the principle of chronometric geodesy. The idea is based on the gravitational redshift, a relativistic effect that predicts that the beat of a clock depends on the speed at which it is moving and the strength of the surrounding gravitational potential. In practice, this means that if we compare the beat of two clocks, then it is possible to directly measure a difference in gravitational potential (or a change in height) between these two clocks. This type of measurement is original because classical geodetic techniques only allow to determine the potential indirectly from gravimetric and classical levelling data. In this work, we model the gravitational signature (potential, acceleration and tensor) of a mass anomaly as a function of its geometry, depth, size and density contrast. These synthetic simulations allow us to identify which types of structures can be detected by clock comparison measurements with a relative frequency uncertainty fixed at 10-17-18-19 (i.e. a vertical sensitivity of less than 10 cm - 1 cm - 1 mm respectively). We are also interested in the spatial resolution required for a clock measurement to detect two mass anomalies depending on its orientation. Finally, we show that this new chronometric observable combined with gravimetry and gradiometry data could allow a better separation of the sources by adding an additional constraint thanks to the medium and long wavelength gravitational information it provides. Numéro de notice : C2023-003 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Poster nature-HAL : Poster-avec-CL DOI : 10.5194/egusphere-egu23-3646 En ligne : https://doi.org/10.5194/egusphere-egu23-3646 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103216
Titre : Towards a transportable Yb lattice clock at SYRTE Type de document : Article/Communication Auteurs : Wilfreddy Moreno, Auteur ; Fatima Rahmouni, Auteur ; Benjamin Pointard, Auteur ; Paul-Eric Pottie, Auteur ; Pacôme Delva, Auteur ; Jérôme Lodewyck, Auteur ; Rodolphe Letargat, Auteur ; J. Romero González, Auteur ; M.-F. Lalancette, Auteur ; Guillaume Lion , Auteur ; Isabelle Panet , Auteur ; Olivier Jamet , Auteur Editeur : New York : Institute of Electrical and Electronics Engineers IEEE Année de publication : 2022 Projets : ROYMAGE / Letargat, Rodolphe Conférence : EFTF-IFCS 2022, Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium 24/04/2022 28/04/2022 Paris France Proceedings IEEE Note générale : bibliographie
This work has received support from Agence Nationale de la Recherche (ANR) with project ROYMAGE (ANR-20-CE47-0006), DIM SIRTEQ and Labex First-TF with project PATHYNAGE, Scientific Council of Observatoire de Paris with project LARYNGITE, and the European Metrology Program for Innovation and Research (EMPIR), with project 18SIB05 ROCIT.
présenté aussi sous "Towards a high flux transportable Ytterbium Optical lattice Clock" aux Houches School of Physics, Cold Atom Predoc School Quantum mixtures, 26 sept-7 oct 2022Langues : Français (fre) Descripteur : [Vedettes matières IGN] Métrologie
[Termes IGN] chronométrie
[Termes IGN] fréquence
[Termes IGN] horloge optique
[Termes IGN] horlogerieRésumé : (auteur) We describe the design of a transportable optical lattice clock based on neutral ytterbium at SYRTE, Observatoire de Paris. This instrument will be connected to the network of ultrastable fiber links REFIMEVE+ with the objective of contributing both to Earth sciences and to frequency metrology. Note de contenu : 2022 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS) Numéro de notice : C2022-034 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Communication nature-HAL : Poster-avec-CL DOI : 10.1109/EFTF/IFCS54560.2022.9850674 Date de publication en ligne : 15/08/2022 En ligne : https://doi.org/10.1109/EFTF/IFCS54560.2022.9850674 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101381 Optimization of optical clock network for the geopotential determination / Guillaume Lion (2019)
Titre : Optimization of optical clock network for the geopotential determination Type de document : Article/Communication Auteurs : Guillaume Lion , Auteur ; Isabelle Panet , Auteur ; David Coulot , Auteur ; Pacôme Delva, Auteur Editeur : Saint-Mandé : Institut national de l'information géographique et forestière - IGN (2012-) Année de publication : 2019 Conférence : AGU 2019 Fall Meeting 09/12/2019 13/12/2019 San Francisco Californie - Etats-Unis programme sans actes Projets : ChronoG2o / Letargat, Rodolphe Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] chronométrie
[Termes IGN] décalage d'horloge
[Termes IGN] horloge optique
[Termes IGN] optimisation (mathématiques)
[Termes IGN] potentiel de pesanteur terrestreRésumé : (auteur) Clock comparisons with an uncertainty at the 10−18 in terms of relative frequency can provide a new kind of measurement to improve our knowledge of Earth’s gravity field and geoid. Instead of using state-of-the-art Earth’s gravitational field models to predict frequency shifts between distant clocks, they could permit determining geopotential differences at a centimeter-level accuracy, and question the possibility of studying geodynamic processes leading to very small vertical deformations or improve the unification of height systems. In our previous work dealing with the geopotential determination at high spatial resolution in mountainous regions, we have pointed out that clock-based geodetic observable can provide useful information at spatial scales beyond what is available from satellites and they could be used to fill areas not covered by the gravity data on the ground. Our synthetic simulations have shown that adding few clock-based potential data to a gravimetric data set can significantly improve the reconstruction of the geopotential. Therefore, it turns out there is a large variety of possible clock distribution allowing to reduce the reconstruction residuals, with different locations and number of clocks. In this work, we investigate ways to optimize clock network from a gravimetric data set in the Massif Central region in order to know where to put them to minimize the residuals and improve further the determination of the geopotential. To do that, we have used a multi-objective genetic algorithm (GA). Starting from a random initial population with different clock distributions, the algorithm selects clock locations with good chances of reproduction and reproduces the new generation of clock locations using genetic operators. The process depends on some objectives we want to reach in order to solve the optimization problem, and it is repeated several times for a given number of generations or until a solution considered as optimum is found. We show how GA can help to provide optimal solutions for a problem with a fixed and variable number of clock locations. We discuss the effect of different parameters, such as the way to define the objectives and the constrains of the problem, the quality of the clock network and the data. Numéro de notice : C2019-057 Affiliation des auteurs : Géodésie+Ext (mi2018-2019) Thématique : POSITIONNEMENT Nature : Poster nature-HAL : Poster-avec-CL DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96833
Titre : Clock measurements to improve the geopotential determination Type de document : Article/Communication Auteurs : Guillaume Lion , Auteur ; Isabelle Panet , Auteur ; Pacôme Delva, Auteur ; David Coulot , Auteur ; Peter Wolf, Auteur ; Sébastien Bize, Auteur ; G. Christine, Auteur Editeur : Munich [Allemagne] : European Geosciences Union EGU Année de publication : 2017 Conférence : EGU 2017, General Assembly 23/04/2017 28/04/2017 Vienne Autriche https://www.egu2017.eu/ Note générale : LE POSTER N'EST PAS ENCORE ACCESSIBLE SUR HAL Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de gravitation
[Termes IGN] géoïde altimétrique
[Termes IGN] horloge optique
[Termes IGN] Massif central (France)
[Termes IGN] méthode des moindres carrés
[Termes IGN] précision centimétrique
[Termes IGN] qualité des donnéesRésumé : (Auteur) Comparisons between optical clocks with an accuracy and stability approaching the 10-18 in term of relative frequency shift are opening new perspectives for the direct determination of geopotential at a centimeter-level accuracy in geoid height. However, so far detailed quantitative estimates of the possible improvement in geoid determination when adding such clock measurements to existing data are lacking. In this context, the present work aims at evaluating the contribution of this new kind of direct measurements in determining the geopotential at high spatial resolution (10 km). We consider the Massif Central area, marked by smooth, moderate altitude mountains and volcanic plateaus leading to variations of the gravitational field over a range of spatial scales. In such type of region, the scarcity of gravity data is an important limitation in deriving accurate high resolution geopotential models. We summarize our methodology to assess the contribution of clock data in the geopotential recovery, in combination with ground gravity measurements. We sample synthetic gravity and disturbing potential data from a spherical harmonics geopotential model, and a topography model, up to 10 km resolution; we also build a potential control grid. From the synthetic data, we estimate the disturbing potential by least-squares collocation. Finally, we assess the quality of the reconstructed potential by comparing it to that of the control grid. We show that adding only a few clock data reduces the reconstruction bias significantly and improves the standard deviation by a factor 3. We discuss the role of different parameters, such as the effect of the data coverage and data quality on these results, the trade-off between the measurement noise level and the number of data, and the optimization of the clock data network. Numéro de notice : C2017-062 Affiliation des auteurs : LASTIG+Ext (2016-2019) Thématique : POSITIONNEMENT Nature : Poster nature-HAL : Poster-sans-CL DOI : sans Date de publication en ligne : 15/07/2022 En ligne : https://hal.science/hal-03724673v1 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101283 Documents numériques
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