A chip-scale atomic clock based on ^87Rb with improved frequency stability
2005; Optica Publishing Group; Volume: 13; Issue: 4 Linguagem: Inglês
10.1364/opex.13.001249
ISSN1094-4087
AutoresSvenja Knappe, Peter Schwindt, Vishal Shah, L. Hollberg, John Kitching, Li‐Anne Liew, John Moreland,
Tópico(s)Advanced Frequency and Time Standards
ResumoWe demonstrate a microfabricated atomic clock physics package based on coherent population trapping (CPT) on the D1 line of 87Rb atoms. The package occupies a volume of 12 mm3 and requires 195 mW of power to operate at an ambient temperature of 200 degrees C. Compared to a previous microfabricated clock exciting the D2 transition in Cs [1], this 87Rb clock shows significantly improved short- and long-term stability. The instability at short times is 4 x?10-11 / tau?/2 and the improvement over the Cs device is due mainly to an increase in resonance amplitude. At longer times (tau?> 50 s), the improvement results from the reduction of a slow drift to ?5 x 10-9 / day. The drift is most likely caused by a chemical reaction of nitrogen and barium inside the cell. When probing the atoms on the D1 line, spin-exchange collisions between Rb atoms and optical pumping appear to have increased importance compared to the D2 line.
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