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Aging studies on micro-fabricated alkali buffer-gas cells for miniature atomic clocks
Résumé We report an aging study on micro-fabricated alkali vapor cells using neon as a buffer gas. An experimental atomic clock setup is used to measure the cell's intrinsic frequency, by recording the clock frequency shift at different light intensities and extrapolating to zero intensity. We find a drift of the cell's intrinsic frequency of (−5.2 ± 0.6) × 10−11/day and quantify deterministic variations in sources of clock frequency shifts due to the major physical effects to identify the most probable cause of the drift. The measured drift is one order of magnitude stronger than the total frequency variations expected from clock parameter variations and corresponds to a slow reduction of buffer gas pressure inside the cell, which is compatible with the hypothesis of loss of Ne gas from the cell due to its permeation through the cell windows. A negative drift on the intrinsic cell frequency is reproducible for another cell of the same type. Based on the Ne permeation model and the measured cell frequency drift, we determine the permeation constant of Ne through borosilicate glass as (5.7 ± 0.7) × 10−22 m2 s−1 Pa−1 at 81 °C. We propose this method based on frequency metrology in an alkali vapor cell atomic clock setup based on coherent population trapping for measuring permeation constants of inert gases.
The authors gratefully acknowledge fruitful discussions with M. Pellaton (Université de Neuchâtel) and S. Karlen (CSEM SA, Neuchâtel, Switzerland) on buffer gas permeation, Y. Pétremand (CSEM) for providing the vapor cells, and D. Varidel (Université de Neuchâtel) for support with the H-maser reference. This work was funded by the Swiss National Science Foundation (FNS) and co-financed by the Swiss Commission for Technology and Innovation (CTI)
   
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Citation S. Abdullah, et al., "Aging studies on micro-fabricated alkali buffer-gas cells for miniature atomic clocks," Applied Physics Letters, vol. 106, p. 1-2, Apr. 2015.
   
Type Article de périodique (Anglais)
Date de publication 22-4-2015
Nom du périodique Applied Physics Letters
Volume 106
Pages 1-2
URL https://doi.org/10.1063/1.4919009