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Science 19 November 2004:
Vol. 306. no. 5700, p. 1255
DOI: 10.1126/science.306.5700.1255c
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This Week in Science

The development of frequency-stabilized sources of laser radiation, together with the associated coupling of frequency cycles in the optical regime, offer the potential to exceed the accuracy set by atomic standards that operate in the lower frequency microwave regime. Margolis et al. (p. 1355) have developed an optical frequency standard based on measuring the transition frequency of a trapped strontium ion. The transition frequency is determined to nearly 1 Hertz in 1015 and represents a fractional uncertainty within a factor of three of the primary cesium atomic-clock standards.




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