Two-Way Optical Frequency Comparisons Over 100km Telecommunication Network Fibers

By using two-way frequency transfer, we demonstrate ultra-high resolution comparison of optical frequencies over a telecommunication fiber link of 100 km operating simultaneously digital data transfer. We first propose and experiment a bi-directional scheme using a single fiber. We show that the relative stability at 1 s integration time is 7 10^18 and scales down to 5 10^21. The same level of performance is reached when an optical link is implemented with an active compensation of the fiber noise. We also implement a real-time two-way frequency comparison over a uni-directional telecommunication network using a pair of parallel fibers. The relative frequency stability is 10^15 at 1 s integration time and reaches 2 10^17 at 40 000 s. The fractional uncertainty of the frequency comparisons was evaluated for the best case to 2 10^20. These results open the way to accurate and high resolution frequency comparison of optical clocks over intercontinental fiber networks

Absolute frequency measurement of 12C16O2 laser lines with a femtosecond laser comb and new determination of the 12C16O2 molecular constants and frequency grid

Absolute frequency measurements of a CO2 laser stabilized on saturated absorption resonances of CO2 laser lines are reported. They were performed using a femtosecond-laser frequency comb generator and two laser diodes at 852 nm and 782 nm as intermediate oscillators, with their frequency difference phase-locked to the CO2 laser. 20 12C16O2 laser lines in the P and R bands at 9 µm were measured with a relative uncertainty of a few 10-12 limited by the CO2 frequency reproducibility. A new determination of the CO2 molecular constants was obtained from these data and previous measurements in the 10 µm band. The CO2 frequency grid was also calculated, with an improvement of two orders of magnitude compared to the previous grid of Maki et al [A.G. Maki, C.C. Chou, K. Evenson, L.R. Zink and J.T. Shy, J. Mol. Spectrosc. 167, (1994) 211-224]

Determination of the Boltzmann constant by laser spectroscopy as a basis for future measurements of the thermodynamic temperature

In this paper, we present the latest results on the measurement of the Boltzmann constant kB, by laser spectroscopy of ammonia at 10 ?m. The Doppler absorption profile of a ro-vibrational line of an NH3 gas sample at thermal and pressure equilibrium is measured as accurately as possible. The absorption cell is placed inside a large 1m3 thermostat filled with an ice-water mixture, which sets the temperature very close to 273.15 K. Analysing this profile, which is related to the Maxwell-Boltzmann molecular speed distribution, leads to a determination of the Boltzmann constant via a measurement of the Doppler width (proportional tosqrt(kBT)). A spectroscopic determination of the Boltzmann constant with an uncertainty as low as 37 ppm is obtained. Recent improvements with a new passive thermostat lead to a temperature accuracy, stability and homogeneity of the absorption cell better than 1 ppm over a day

Evidence for speed-dependent effects in NH3 self-broadened spectra: towards a new determination of the Boltzmann constant

In this paper we present an accurate analysis of the shape of an isolated rovibrational ammonia line from the strong nu2 band around 10 $\mu$m, recorded by laser absorption spectroscopy. Experimental spectra obtained under controlled temperature and pressure, are confronted to various models that take into account Dicke narrowing or speed-dependent effects. Our results show clear evidence for speed-dependent broadening and shifting, which had never been demonstrated so far in NH3. Accurate lineshape parameters of the nu2 saQ(6,3) line are obtained. Our current project aiming at measuring the Boltzmann constant, kB, by laser spectroscopy will straight away benefit from such knowledge. We anticipate that a first optical determination of kB with a competitive uncertainty of a few ppm is now reachable.Comment: 13 pages, 5 figures, 1 tabl

Measurement of the Boltzmann constant by the Doppler broadening technique at a 3,8x10-5 accuracy level

In this paper, we describe an experiment performed at the Laboratoire de Physique des Lasers and dedicated to an optical measurement of the Boltzmann constant. With the proposed innovative technique, determining comes down to an ordinary frequency measurement. The method consists in measuring as accurately as possible the Doppler absorption profile of a rovibrational line of ammonia in thermal equilibrium. This profile is related to the Maxwell-Boltzmann molecular velocity distribution along the laser beam. A fit of the absorption line shape leads to a determination of the Doppler width proportional to sqrt(kT) and thus to a determination of the Boltzmann constant. The laser source is an ultra-stable CO2 laser with a wavelength . The absorption cell is placed in a thermostat keeping the temperature at 273.15 K within 1.4 mK. We were able to measure with a relative uncertainty as small as 3.8x10-5, which represents an improvement of an order of magnitude for an integration time comparable to our previous measurement published in 2007 [1

Probing weak force induced parity violation by high resolution mid-infrared molecular spectroscopy

To date no experiment has reached the level of sensitivity required to observe weak nuclear force induced parity violation (PV) energy differences in chiral molecules. In this paper, we present the approach, adopted at Laboratoire de Physique des Lasers (LPL), to measure frequency differences in the vibrational spectrum of enantiomers. We review different spectroscopic methods developed at LPL leading to the highest resolutions, as well as 20 years of CO2 laser stabilization work enabling such precise measurements. After a first attempt to observe PV vibrational frequency shifts using sub-Doppler saturated absorption spectroscopy in a cell, we are currently aiming at an experiment based on Doppler-free two-photon Ramsey interferometry on a supersonic beam. We report on our latest progress towards observing PV with chiral organo-metallic complexes containing a heavy rhenium atom

Gouverner la scène (le système panoptique du comédien LeKain)

Ce travail a pour objet de comprendre les évolutions majeures de la pratique théâtrale au XVIIIe siècle,à travers l analyse de sources manuscrites inédites du Comédien-Français Henri-Louis LeKain. Figureauto-constituée de souverain des planches , LeKain n a eut de cesse de vouloir réformer les modesde production et de fabrication théâtrales de son temps. En quoi le rapport de force qu il instaure avectoutes les instances de décision et de pouvoir de la Comédie éclaire-t-il justement les mutations encours ? Quelles sont ses revendications ? Comment et pourquoi émergent-elles dans le champ théâtralde l époque ? Quelles sont les stratégies mises en place par LeKain pour parvenir à ses fins ? En quoiconsiste cette tentative de prise de pouvoir sur l ensemble du champ théâtral ? Pourquoi et commentcette va-t-elle esthétiquement et politiquement marquer les modes de gouvernance de la scène enFrance ? Le Registre et tout l appareil écrit qui l entoure et l accompagne, procèdent autant, voiremoins, d une tentative de fixer la mise en scène des tragédies retenues par le comédien que d unevolonté d arriver à la définition d un Théâtre idéal dont LeKain se donne pour être tout à la fois leconcepteur et le dépositaire exclusif. En cherchant à se placer au centre d un dispositif de productiondont il entend surveiller tous les aspects artistiques, politiques, économiques, moraux LeKaindéfinit les contours d un système de contrôle très proche du système panoptique définit par Foucaultdans Surveiller et Punir.The aim of this study is to understand the major changes in theatrical practice in the 18th century,through an analysis of unpublished manuscript sources, written by the French actor Henri-LouisLeKain. Self-appointed king of the boards , LeKain never ceased in his striving to update anddevelop the practice of theatrical production and presentation. To what extent does the power-strugglehe initiated with the decision makers at the the Comédie-Française, throw light on the changes takingplace ? What were his demands ? How did they emerge in the theatrical world of the time, and why ?What strategies did LeKain pursue to achieve his goals ? What did this attempt to seize power consistof in the wider field of theatre ? And how does it affect the governance of French theatrical productionin the widest political and aesthetic sense ? The Registre and all surrounding and accompanyingwritten material arise from LeKain s desire to arrive at a definition of a theatrical ideal, of which heconsidered himself both the originator and sole repository, and to a lesser extent, from an attempt toformalise the production of the tragedies that he had commissioned.By attempting to place himself at the heart of an apparatus of production such that he could watchover every aspect artistic, political, economic and moral LeKain defined the outlines of a system ofcontrol very similar to the panoptic gaze defined by Foucault in Surveiller et Punir.NANTERRE-PARIS10-Bib. élec. (920509901) / SudocSudocFranceF

Mid-IR frequency measurement using an optical frequency comb and a long-distance remote frequency reference

We have built a frequency chain which enables to measure the absolute frequency of a laser emitting in the 28-31 THz frequency range and stabilized onto a molecular absorption line. The set-up uses an optical frequency comb and an ultrastable 1.55 $\mu$m frequency reference signal, transferred from LNE-SYRTE to LPL through an optical link. We are now progressing towards the stabilization of the mid-IR laser via the frequency comb and the extension of this technique to quantum cascade lasers. Such a development is very challenging for ultrahigh resolution molecular spectroscopy and fundamental tests of physics with molecules

A revised uncertainty budget for measuring the Boltzmann constant using the Doppler Broadening Technique on ammonia

We report on our on-going effort to measure the Boltzmann constant, kB, using the Doppler Broadening Technique. The main systematic effects affecting the measurement are discussed. A revised error budget is presented in which the global uncertainty on systematic effects is reduced to 2.3 ppm. This corresponds to a reduction of more than one order of magnitude compared to our previous Boltzmann constant measurement. Means to reach a determination of kB at the part per million accuracy level are outlined