Faculté des sciences

Improvement of the frequency stability below the dick limit with a continuous atomic fountain clock

Devenoges, Laurent ; Stefanov, A. ; Joyet, Alain ; Thomann, Pierre ; Di Domenico, Gianni

In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2012, vol. 59, no. 2, p. 211-216

The frequency instability of a shot-noise limited atomic fountain clock is inversely proportional to its signal-to- noise ratio. Therefore, increasing the atomic flux is a direct way to improve the stability. Nevertheless, in pulsed operation, the local oscillator noise limits the performance via the Dick effect. We experimentally demonstrate here that a continuous atomic fountain allows one to... Plus

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    Summary
    The frequency instability of a shot-noise limited atomic fountain clock is inversely proportional to its signal-to- noise ratio. Therefore, increasing the atomic flux is a direct way to improve the stability. Nevertheless, in pulsed operation, the local oscillator noise limits the performance via the Dick effect. We experimentally demonstrate here that a continuous atomic fountain allows one to overcome this limitation. In this work, we take advantage of two-laser optical pumping on a cold cesium beam to increase the useful fountain flux and, thus, to reduce the frequency instability below the Dick limit. A stabil- ity of 6 • 10-14 τ-1/2 has been measured with the continuous cesium fountain FOCS-2.