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Absolute frequency measurements of the Hg+ and Ca optical clock transitions with a femtosecond laser.
- Source :
-
Physical review letters [Phys Rev Lett] 2001 May 28; Vol. 86 (22), pp. 4996-9. - Publication Year :
- 2001
-
Abstract
- The frequency comb created by a femtosecond mode-locked laser and a microstructured fiber is used to phase coherently measure the frequencies of both the Hg+ and Ca optical standards with respect to the SI second. We find the transition frequencies to be f(Hg) = 1 064 721 609 899 143(10) Hz and f(Ca) = 455 986 240 494 158(26) Hz, respectively. In addition to the unprecedented precision demonstrated here, this work is the precursor to all-optical atomic clocks based on the Hg+ and Ca standards. Furthermore, when combined with previous measurements, we find no time variations of these atomic frequencies within the uncertainties of the absolute value of( partial differential f(Ca)/ partial differential t)/f(Ca) < or =8 x 10(-14) yr(-1) and the absolute value of(partial differential f(Hg)/ partial differential t)/f(Hg) < or =30 x 10(-14) yr(-1).
Details
- Language :
- English
- ISSN :
- 0031-9007
- Volume :
- 86
- Issue :
- 22
- Database :
- MEDLINE
- Journal :
- Physical review letters
- Publication Type :
- Academic Journal
- Accession number :
- 11384404
- Full Text :
- https://doi.org/10.1103/PhysRevLett.86.4996