Design Details of FOCS-2, an Improved Continuous Cesium Fountain Frequency Standard

Fiizesi, F.; Plimmer, Mark; Dudle, G.; Guéna, Jocelyne; Thomann, P.

doi:10.1109/freq.2007.4319038

Cited by 2 publications

(1 citation statement)

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“…This work emphasizes the advantage of a continuous fountain in reducing intermodulation-related local oscillator noise and opens the possibility of reducing significantly the short-term instability via an increase in the atomic flux. To this end, we have designed and built a second continuous atomic fountain standard [12].…”

Section: Discussionmentioning

confidence: 99%

Experimental demonstration of intermodulation effects in a continuous cesium fountain microwave frequency standard

Guéna

Dudle

Plimmer

et al. 2007

2007 IEEE International Frequency Control Symposium Joint With the 21st European Frequency and Time Forum

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The short-term stability of passive atomic frequency standards, particularly ones operated sequentially, is often limited by local oscillator noise via intermodulation effects. This article describes an experimental demonstration of the intermodulation effect on the frequency stability of a continuous atomic fountain standard usually imperceptible under normal operating conditions. To make the effect observable, we increase the phase instability of the microwave field interrogating the clock transition. We measure the frequency stability of the locked, commercial local oscillator, for both square-wave phase modulation and squarewave frequency modulation of the microwave field. The observed degradation of the stability depends on the modulation frequency in a way that agrees with our earlier theoretical predictions. Most significantly, no degradation is observed when the modulation frequency is made equal to the Ramsey linewidth. When no extra phase noise is added, the frequency instability, currently 2.0×10 −13 at 1 s, is limited only by atomic shot-noise. This shows the potential to reduce it via the use of a higher atomic flux.

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Section: Discussionmentioning

confidence: 99%