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Search Results: 1 - 10 of 14787 matches for " Christian Chardonnet "
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Progress towards an accurate determination of the Boltzmann constant by Doppler spectroscopy
Cyril Lemarchand,Meriam Triki,Beno?t Darquié,Christian J. Bordé,Christian Chardonnet,Christophe Daussy
Physics , 2010, DOI: 10.1088/1367-2630/13/7/073028
Abstract: In this paper, we present significant progress performed on an experiment dedicated to the determination of the Boltzmann constant, k, by accurately measuring the Doppler absorption profile of a line in a gas of ammonia at thermal equilibrium. This optical method based on the first principles of statistical mechanics is an alternative to the acoustical method which has led to the unique determination of k published by the CODATA with a relative accuracy of 1.7 ppm. We report on the first measurement of the Boltzmann constant by laser spectroscopy with a statistical uncertainty below 10 ppm, more specifically 6.4 ppm. This progress results from improvements in the detection method and in the statistical treatment of the data. In addition, we have recorded the hyperfine structure of the probed saQ(6,3) rovibrational line of ammonia by saturation spectroscopy and thus determine very precisely the induced 4.36 (2) ppm broadening of the absorption linewidth. We also show that, in our well chosen experimental conditions, saturation effects have a negligible impact on the linewidth. Finally, we draw the route to future developments for an absolute determination of with an accuracy of a few ppm.
High-resolution optical frequency dissemination on a telecommunication network with data traffic
Fabien Kéfélian,Olivier Lopez,Haifeng Jiang,Christian Chardonnet,Anne Amy-Klein,Georgio Santarelli
Physics , 2009, DOI: 10.1364/OL.34.001573
Abstract: We transferred the frequency of an ultra-stable laser over a 108 km urban fiber link comprising 22 km of optical communications network fiber simultaneously carrying Internet data traffic. The metrological signal and the digital data signal are transferred on two different frequency channels in a dense wavelength division multiplexing scheme. The metrological signal is inserted into and extracted from the communications network by using bidirectional off-the-shelf optical add-drop multiplexers. The link-induced phase noise is measured and cancelled with round-trip technique using an all-fiber-based interferometer. The compensated link shows an Allan deviation of a few 10-16 at one second and below 10-19 at 10,000 seconds. This opens the way to a wide dissemination of ultra stable optical clock signals between distant laboratories via the Internet network.
Stability of the proton-to-electron mass ratio
Alexander Shelkovnikov,Robert James Butcher,Christian Chardonnet,Anne Amy-Klein
Physics , 2008, DOI: 10.1103/PhysRevLett.100.150801
Abstract: We report a limit on the fractional temporal variation of the proton-to-electron mass ratio as, obtained by comparing the frequency of a rovibrational transition in SF6 with the fundamental hyperfine transition in Cs. The SF6 transition was accessed using a CO2 laser to interrogate spatial 2-photon Ramsey fringes. The atomic transition was accessed using a primary standard controlled with a Cs fountain. This result is direct and model-free.
Ultra-stable long distance optical frequency distribution using the Internet fiber network
Olivier Lopez,Adil Haboucha,Bruno Chanteau,Christian Chardonnet,Anne Amy-Klein,Giorgio Santarelli
Physics , 2012, DOI: 10.1364/OE.20.023518
Abstract: We report an optical link of 540 km for ultrastable frequency distribution over the Internet fiber network. The stable frequency optical signal is processed enabling uninterrupted propagation on both directions. The robustness and the performance of the link are enhanced by a cost effective fully automated optoelectronic station. This device is able to coherently regenerate the return optical signal with a heterodyne optical phase locking of a low noise laser diode. Moreover the incoming signal polarization variation are tracked and processed in order to maintain beat note amplitudes within the operation range. Stable fibered optical interferometer enables optical detection of the link round trip phase signal. The phase-noise compensated link shows a fractional frequency instability in 10 Hz bandwidth of 5x10-15 at one second measurement time and 2x10-19 at 30 000 s. This work is a significant step towards a sustainable wide area ultrastable optical frequency distribution and comparison network.
Two-Way Optical Frequency Comparisons Over 100km Telecommunication Network Fibers
Anthony Bercy,Fabio Stefani,Olivier Lopez,Christian Chardonnet,Paul-Eric Pottie,Anne Amy-Klein
Physics , 2014, DOI: 10.1103/PhysRevA.90.061802
Abstract: 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 an SF6 two-photon line using a femtosecond optical comb and sum-frequency generation
Anne Amy-Klein,Andrei Goncharov,Mickael Guinet,Christophe Daussy,Olivier Lopez,Alexander Shelkovnikov,Christian Chardonnet
Physics , 2005, DOI: 10.1364/OL.30.003320
Abstract: We demonstrate a new simple technique to measure IR frequencies near 30 THz using a femtosecond (fs) laser optical comb and sum-frequency generation. The optical frequency is directly compared to the distance between two modes of the fs laser, and the resulting beat note is used to control this distance which depends only on the repetition rate fr of the fs laser. The absolute frequency of a CO2 laser stabilized onto an SF6 two-photon line has been measured for the first time. This line is an attractive alternative to the usual saturated absorption OsO4 resonances used for the stabilization of CO2 lasers. First results demonstrate a fractional Allan deviation of 3.10-14 at 1 s.
First direct determination of the Boltzmann constant by an optical method
Christophe Daussy,Mickael Guinet,Anne Amy-Klein,Khelifa Djerroud,Yves Hermier,Stephan Briaudeau,Christian J. Bordé,Christian Chardonnet
Physics , 2007, DOI: 10.1103/PhysRevLett.98.250801
Abstract: We have recorded the Doppler profile of a well-isolated rovibrational line in the \nu2 band of 14NH3. Ammonia gas was placed in an absorption cell thermalized by a water-ice bath. By extrapolating to zero pressure, we have deduced the Doppler width which gives a first measurement of the Boltzmann constant, kB, by laser spectroscopy. A relative uncertainty of 2x10-4 has been obtained. The present determination should be significantly improved in the near future and contribute to a new definition of the kelvin.
86-km optical link with a resolution of 2.10-18 for RF frequency transfer
Olivier Lopez,Anne Amy-Klein,Christophe Daussy,Christian Chardonnet,Fran?ois Narbonneau,Michel Lours,Georgio Santarelli
Physics , 2007, DOI: 10.1140/epjd/e2008-00059-5
Abstract: RF frequency transfer over an urban 86 km fibre has been demonstrated with a resolution of 2.10-18 at one day measuring time using an optical compensator. This result is obtained with a reference carrier frequency of 1 GHz, and a rapid scrambling of the polarisation state of the input light in order to reduce the sensitivity to the polarisation mode dispersion in the fibre. The limitation due to the fibre chromatic dispersion associated with the laser frequency fluctuations is highlighted and analyzed. A preliminary test of an extended compensated link over 186 km using optical amplifiers gives a resolution below 10-17 at 1 day.
Frequency Measurement of an Ar+ Laser Stabilized on Narrow Lines of Molecular Iodine at 501.7 nm
Frederic Du Burck,Christophe Daussy,Anne Amy-Klein,Andrei N. Goncharov,Olivier Lopez,Christian Chardonnet,Jean-Pierre Wallerand
Physics , 2004,
Abstract: A spectrometer for ultra high-resolution spectroscopy of molecular iodine at wave length 501.7 nm, near the dissociation limit is described. Line shapes about 30 kHz wide (HWHM) were obtained using saturation spectroscopy in a pumped cell. The frequency of an Ar+ laser was locked to a hyperfine component of the R(26)62-0 transition and the first absolute frequency measurement of this line is reported.
Evidence for speed-dependent effects in NH3 self-broadened spectra: towards a new determination of the Boltzmann constant
Meriam Triki,Cyril Lemarchand,Beno?t Darquié,Papa Lat Tabara Sow,Vincent Roncin,Christian Chardonnet,Christophe Daussy
Physics , 2012, DOI: 10.1103/PhysRevA.85.062510
Abstract: 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.
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