First results with a cold cesium continuous fountain resonator

Dudle, G.; Joyet, A.; Berthoud, P.; Mileti, G.; Thomann, P.

doi:10.1109/19.918179

Cited by 20 publications

(13 citation statements)

References 13 publications

(18 reference statements)

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“…(14) to be N d = 1.7 × 10 5 . On the other hand, in the case of 3D optical molasses, the number of detected atoms is calculated from Eq.…”

Section: A Atomic Densitymentioning

confidence: 99%

“…To improve the uncertainty arising from a collisional shift without sacrificing frequency stability, several approaches have been attempted. For example, to decrease the atomic density while maintaining the number of detected atoms, a continuous atomic beam fountain [14,15] and a juggling fountain [12,16,17], in which several atomic clouds are launched at intervals and simultaneously arrive at the detection region, have been studied. On the other hand, to measure the collisional shift more precisely, an adiabatic rapid passage method, in which the number of atoms is finely controlled without changing their density distribution and the temperature, has been investigated [18].…”

Section: Introductionmentioning

confidence: 99%

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Proposal of a truncated atomic beam fountain for reduction of collisional frequency shift

et al. 2010

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We propose an atomic fountain clock with a truncated cold atomic beam to achieve both a low collisional frequency shift and high frequency stability. In this clock, the launching velocity of a cold atomic beam can be swept to reduce the atomic density in the interrogation region for the Ramsey resonance and to increase the atomic density in the detection region. Before the top of the beam arrives at the interrogation region, the cold atomic beam is truncated by turning off the cooling laser beams to remove the unnecessary light shift. The atomic density in the interrogation region is theoretically evaluated to be 0.04 times that in an ordinary atomic fountain with optical molasses for the same number of detected atoms. The frequency stability limit due to quantum projection noise is calculated to reach 6.4 × 10 −14 in 1 s from the number of detected atoms while the fractional collisional shift is estimated to be ∼ −2 × 10 −16 .

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“…(14) to be N d = 1.7 × 10 5 . On the other hand, in the case of 3D optical molasses, the number of detected atoms is calculated from Eq.…”

Section: A Atomic Densitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Proposal of a truncated atomic beam fountain for reduction of collisional frequency shift

et al. 2010

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“…Beyond that, it is expected that independent daily clock estimates will have white noise-distributed errors and follow a τ −1 Allan deviation, shown by the dashed black line. For comparison, the red trend indicates the design goal for the METAS Cs fountain [53] and the blue trend is for a Sigma Tau H-maser (from Symmetricon). The fundamental geodetic limit is represented by the lower blue band, based on the repeatability of station height measurements.…”

Section: Linkmentioning

confidence: 99%

Geodetic techniques for time and frequency comparisons using GPS phase and code measurements

2005

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We review the development and status of GPS geodetic methods for high-precision global time and frequency comparisons. A comprehensive view is taken, including hardware effects in the transmitting satellites and tracking receiver stations, data analysis and interpretation, and comparisons with independent results. Other GPS techniques rely on single-frequency data and/or assume cancellation of most systematic errors using differences between simultaneous observations. By applying the full observation modelling of modern geodesy to dual-frequency observations of GPS carrier phase and pseudorange, the precision of timing comparisons can be improved from the level of several nanoseconds to near 100 ps. For an averaging interval of one day, we infer a limiting Allan deviation of about 1.4 × 10 −15 for the GPS geodetic technique. The accuracy of time comparisons is set by the ability to calibrate the absolute instrumental delays through the GPS receiver and antenna chain, currently about 3 ns. Geodetic clock measurements are available for most of the major timing laboratories, as well as for many other tracking stations and the satellites, via the routine products of the International GPS Service.

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“…c) The continuous fountain [9][10][11] which allows one to reduce simultaneously intermodulation effects and collisional shifts by more than two orders of magnitude. This relaxes, by the same margin, the compromise faced in most pulsed fountains between high stability (but high collisional shift and uncertainty), and high accuracy (but moderate frequency stability), without resorting to a better oscillator than state-ofthe-art, space qualified, quartz oscillators.…”

Section: Short Time Stability and Reduction Of Intermodulation Effectsmentioning

confidence: 99%

“…1, together with its main operating characteristics. As described in detail in [9][10][11], the continuous beam is produced from a 3D molasses with three pairs of counter- propagating beams, orthogonal to each other, one horizontal and two at 45…”

Section: The Continuous Cold Cs Fountain Focs-1mentioning

confidence: 99%