Le Touquet – Paris-Plage, France
Le Touquet – Paris-Plage, France

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Beyer A.,Max Planck Institute of Quantum Optics | Parthey Ch.G.,Max Planck Institute of Quantum Optics | Kolachevsky N.,Max Planck Institute of Quantum Optics | Alnis J.,Max Planck Institute of Quantum Optics | And 15 more authors.
Journal of Physics: Conference Series | Year: 2013

Precise determinations of transition frequencies of simple atomic systems are required for a number of fundamental applications such as tests of quantum electrodynamics (QED), the determination of fundamental constants and nuclear charge radii. The sharpest transition in atomic hydrogen occurs between the metastable 2S state and the 1S ground state. Its transition frequency has now been measured with almost 15 digits accuracy using an optical frequency comb and a cesium atomic clock as a reference [1]. A recent measurement of the 2S-2P3/2 transition frequency in muonic hydrogen is in significant contradiction to the hydrogen data if QED calculations are assumed to be correct [2, 3]. We hope to contribute to this so-called "proton size puzzle" by providing additional experimental input from hydrogen spectroscopy. © Published under licence by IOP Publishing Ltd.


Kozlova O.,LNE SYRTE | Kozlova O.,Laboratoire Communications Of Metrologie Lne Cnam | Danet J.-M.,LNE SYRTE | Guerandel S.,LNE SYRTE | De Clercq E.,LNE SYRTE
IEEE Transactions on Instrumentation and Measurement | Year: 2014

Vapor cell atomic clocks exhibit reduced frequency stability for averaging time between about one hundred and a few thousand seconds. Here we report a study on the impact of the main parameters on the mid-to-long term instability of a buffer-gas vapor cell Cs clock, based on coherent population trapping (CPT). The CPT signal is observed on the Cs $D1$ line transmission, using a double Λ scheme and a Ramsey interrogation technique. The effects on the clock frequency of the magnetic field, the cell temperature, and the laser intensities are reported. We show in particular that the laser intensity shift is temperature dependent. Along with the laser intensity ratio and laser polarization properties, this is one of the most important parameters. © 1963-2012 IEEE.


Le Targat R.,LNE SYRTE | Lorini L.,INRIM - Istituto Nazionale di Ricerca Metrologica | Gurov M.,LNE SYRTE | Zawada M.,Nicolaus Copernicus University | And 4 more authors.
EFTF 2012 - 2012 European Frequency and Time Forum, Proceedings | Year: 2012

Two optical lattice clocks operated on the transition 1S 0-3P0 of the 87Sr atom are now operational at the LNE-SYRTE laboratory, their comparison aims at demonstrating that no systematic effect has been overlooked in their respective accuracy budgets. In this proceeding we focus only on trapping effects, we discuss technical aspects of the calibration of the lattice induced light shifts, and we show the observation of the second order light shift. Data resulting from the comparisons are reported and discussed. © 2012 IEEE.


Thomas M.,French National Laboratory of Metrology and Testing | Espel P.,French National Laboratory of Metrology and Testing | Ziane D.,French National Laboratory of Metrology and Testing | Pinot P.,French National Conservatory of Arts and Crafts | And 5 more authors.
Metrologia | Year: 2015

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. © 2015 BIPM & IOP Publishing Ltd.


Delporte J.,French National Center for Space Studies | Suard N.,French National Center for Space Studies | Uhrich P.,LNE SYRTE | Tuckey P.,LNE SYRTE
2013 Joint European Frequency and Time Forum and International Frequency Control Symposium, EFTF/IFC 2013 | Year: 2013

EGNOS is the European Satellite Based GPS Augmentation System. It generates its own time scale (ENT) that is steered to GPS time. The time offset between ENT and UTC (actually UTC(OP)) is contained in EGNOS Message Type 12. The aim of this paper is to validate the content of this message and to present the performances of ENT with respect to UTC and GPS time over more than 4 years. © 2013 IEEE.


Laas-Bourez M.,University of Nice Sophia Antipolis | Samain E.,University of Nice Sophia Antipolis | Courde C.,University of Nice Sophia Antipolis | Oneto J.-L.,University of Nice Sophia Antipolis | And 5 more authors.
2013 Joint European Frequency and Time Forum and International Frequency Control Symposium, EFTF/IFC 2013 | Year: 2013

The Time Transfer by Laser Link (T2L2)[1) experiment aim to synchronise remote ultra stable clocks over large-scaled distances using two laser ranging stations. T2L2 ultimate time transfer capability can only be demonstrate with a picosecond range ground mastering. We focus this year in knowledge and equipment improvement to perform a T2L2 time transfer with accuracy and stability of a few picoseconds. A deep analysis of signals stability has been carried out this year in the time and frequency laboratory in Plateau de Calern. The aim was to better understand the limits and hardware configuration and to enhance time and frequency distribution for T2L2 experiment. We showed phase noise and stability problem on our H-maser distribution. Final measures were conducted in October in collaboration with SYRTE. Then a complete equipment reorganisation was done. This paper focus on the time and frequency laboratory characterization before and after the reorganisation. We introduce our new equipments and present our new H-maser time scale and discuss the performances obtained. © 2013 IEEE.


Hrabina J.,Institute of Scientific Instruments | Sarbort M.,Institute of Scientific Instruments | Hola M.,Institute of Scientific Instruments | Cip O.,Institute of Scientific Instruments | And 4 more authors.
2016 European Frequency and Time Forum, EFTF 2016 | Year: 2016

This work is oriented to comparison of methods for iodine absorption cells quality evaluation. Optical frequency references based on molecular iodine represent one of the most used references for stabilizion of laser standards working at visible spectral range. Unfortunately iodine is a media with very high sensitivity to contamination so the chemical purity of iodine cells must be preciselly controlled. Traditional methods for iodine absorption cells quality checking have several difficulties and disadvantages, these problems complicate their common using in labs. Due to this reason we propose an alternative method of spectral linewidths measurement, which overcomes these difficulties of traditionally used approaches and which serves as a tool for iodine cells quality evaluation. In this work we present the results of comparison of two laser induced fluorescence setups (with and without the compensation for the laser source spectral mode-hops) with proposed method of selected hyperfine transition linewidth measurements and we discuss advantages and limitations of these methods for practical using. © 2016 IEEE.


Kanj A.,LNE SYRTE | Achkar J.,LNE SYRTE | Rovera D.,LNE SYRTE
EFTF 2012 - 2012 European Frequency and Time Forum, Proceedings | Year: 2012

The Two-Way Satellite Time and Frequency Transfer (TWSTFT) is widely used by the time institutes to compare ground atomic clocks and contributes to the production of the Temps Atomique International (TAI) calculated by the BIPM. In the past, TWSTFT links have frequency stability of 1×10-15 at one day [1], and since the last three years, two-way links became more and more noisy and the frequency stability has been degraded which has motivated the present work. In order to improve the performance of the TWSTFT technique, we focused on the principle parameters that impact the measurements stability and accuracy. In completion to the previous work [2] on the measurement noise in TWSTFT, we analyzed the impact of the changes of reference clock, satellite and satellite transponder on the two-way link instability over the period of the last five years. In addition, we studied the contribution in measurement noise on the two-way links of the following parameters: the chip-rates of the pseudo random noise modulation of the transmitted signal, the power of the transmitted and received signals. We also use the satellite simulator to determine the dependence of the chip rates on the delay difference of the OP ground stations. We completed the work in analyzing the variation of the short term residual noise fluctuations [3] and the carrier to noise ratio of the received signals in function of the previously listed parameters. Different results are presented in this paper and possible issues for improvement of the two-way links are proposed. © 2012 IEEE.


Kanj A.,LNE SYRTE | Achkar J.,LNE SYRTE | Rovera D.,LNE SYRTE
EFTF 2012 - 2012 European Frequency and Time Forum, Proceedings | Year: 2012

The TWSTFT carrier phase technique permits to improve the short term stability of the two-way links. The basic idea of this method is to calculate the offset between the frequencies of the two remote clocks in comparison. The frequency of the local oscillator on-board and Doppler coefficients are also determined. By applying the carrier phase method using the two OP ground stations in a common clock mode, a frequency stability of 110-12 is reached at 1 s while with the OP satellite simulator, a value of 410 -13 is achieved. © 2012 IEEE.


PubMed | LNE SYRTE
Type: Journal Article | Journal: Physical review letters | Year: 2011

We report on the Lamb-Dicke spectroscopy of the doubly forbidden (6s(2))(1)S(0)(6s6p)(3)P(0) transition in (199)Hg atoms confined to a vertical 1D optical lattice. With lattice trapping of 10(3) atoms and a 265.6 nm probe laser linked to the LNE-SYRTE primary frequency reference we have determined the center frequency of the transition for a range of lattice wavelengths and at two lattice trap depths. We find the Stark-free (magic) wavelength to be 362.53(0.21) nm-essential knowledge for future use of this line in a clock with anticipated 10(-18) range accuracy. We also present evidence of the laser excitation of a Wannier-Stark ladder of states in a lattice of well depth 10E(R).

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