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We report the operation of a dual Rb/Cs atomic fountain clock. 133Cs and 87Rb atoms are cooled, launched, and detected simultaneously in LNE-SYRTE's FO2 double fountain. The dual clock operation occurs with no degradation of either the stability or the accuracy. We describe the key features for achieving such a simultaneous operation. We also report on the results of the first Rb/Cs frequency measurement campaign performed with FO2 in this dual atom clock configuration, including a new determination of the absolute 87Rb hyperfine frequency. [ABSTRACT FROM AUTHOR]

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-SYFTE 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. [ABSTRACT FROM AUTHOR]

Optical clocks have fractional frequency uncertainty of 1E-18 and will continue to progress. Coherence optical fiber links over distances of thousands of kilometers can support comparisons to 1E-19 or better and are technologically mature. Clocks comparisons at this level of uncertainty can provide measurements of gravitational potential difference at the 1 cm level. This approach can provide novel data for geodesy and Earth science. In my presentation, I will review the status of clocks and clock comparison capabilities. I will discuss theoretical studies of how clock data can be combined with other data to improve gravity field models. I will discuss possibilities to move toward pilot experiments in chronometric geodesy. [ABSTRACT FROM AUTHOR]

The article presents information about an ultra stable optical laser which is based on a single-crystal silicon Fabry-Pérot cavity in order to provide fractional frequency instability of 1 × 10-16. It mentions that precision optical interferometers are used for those measurements which require utmost accuracy. It also states optical atomic clock, based on microwave transitions and probed with ultra stable laser.