This paper focuses on the development of tools aiming to solve several problems related to the microwave interrogation signal in atomic fountains. We first consider the problem related to cycle ...synchronous phase transients caused by the sequential operation of the atomic fountain. To search for such systematic phase variations deeply buried in the microwave synthesizer phase noise, we have developed a novel triggered-phase transient analyzer capable of processing the microwave signal to extract the phase in a synchronous manner even in the presence of frequency modulation. With this device we check in vivo the LNE-SYRTE fountain's interrogation signals with a resolution approaching 1 microradian. In addition, using this device, we investigate an innovative approach to solve a second problem, namely, the shift caused by microwave leakage in the fountain. Our approach consists of switching off the fountain microwave interrogation signal when atoms are outside the microwave cavity. To do that, we have developed a switch that is almost free of phase transients and is thus able to eliminate the frequency shift caused by microwave leakage without inducing significant phase transients on the interrogation signal.
In this paper we describe the improved redesign of the microwave frequency synthesizers for Laboratoire National d'Essais-Systemes de Reference Temps-Espace (LNE-SYRTE) atomic fountains. The ...synthesizers use a cryogenic oscillator to generate both Cs and Rb hyperfine frequencies based on a new distribution frequency of 1 GHz. The main metrological features (phase noise, long-term phase stability, and spectral purity) of the synthesizers have been measured in situ connected to an atomic fountain and are compatible with an accuracy goal of 10 -16 for the atomic fountains. The simultaneous test of two different synthesizers on the FO2 atomic fountain at the 10 -16 level also is reported
We report on a new experiment that tests for a violation of Lorentz invariance (LI), by searching for a dependence of atomic transition frequencies on the orientation of the spin of the involved ...states (Hughes-Drever type experiment). The atomic frequencies are measured using a laser cooled 133Cs atomic fountain clock, operating on a particular combination of Zeeman substates. We analyze the results within the framework of the Lorentz violating standard model extension (SME), where our experiment is sensitive to a largely unexplored region of the SME parameter space, corresponding to first measurements of four proton parameters and improvements by 11 and 13 orders of magnitude on the determination of four others. In spite of the attained uncertainties, and of having extended the search into a new region of the SME, we still find no indication of LI violation.
An optical lattice clock with spin-polarized 87Sr atoms Baillard, X.; Fouché, M.; Le Targat, R. ...
The European physical journal. D, Atomic, molecular, and optical physics,
2008/06, Letnik:
48, Številka:
1
Journal Article
Recenzirano
Odprti dostop
.
We present a new evaluation of an
87
Sr optical lattice clock using spin polarized atoms. The frequency of the
1
S
0
→
3
P
0
clock transition is found to be 429 228 004 229 873.6 Hz with a ...fractional uncertainty of 2.6×10
-15
, a value that is comparable to the frequency difference between the various primary standards throughout the world. This measurement is in excellent agreement with a previous one of similar accuracy Phys. Rev. Lett.
98
, 083002 (2007).
This paper reports our works on the 3 LNE-SYRTE fountains and their frequency comparisons. We have performed new experiments on the frequency shifts related to the microwave synthesis and to the ...blackbody radiation interaction. We have also refined the accuracy budget of the 87 Rb hyperfine splitting and obtained a new measurement of the frequency comparison between Cesium and Rubidium.
We review our recent Michelson-Morley (MM) and Kennedy-Thorndike (KT) experiment, which tests Lorentz invariance in the photon sector, and report first results of our ongoing atomic clock test of ...Lorentz invariance in the matter sector.
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