Standards of time and frequency at the outset of the 21st century

Published

November 19, 2004

Author(s)

Scott Diddams, James C. Bergquist, Steven R. Jefferts, Christopher W. Oates

Abstract

In this paper we review state-of-the-art atomic time and frequency standards and discuss some of their uses in science and technology. After fifty years of development, microwave atomic clocks based on cesium have achieved fractional uncertainties below 1 part in 1015; a level unequaled in all of metrology. The past five years have seen accelerated development of optical atomic clocks, which hold significant potential for still improved timekeeping. Time and frequency standards with various levels of performance are ubiquitous in our modern society, finding applications in many technological fields as well as in the continued exploration of the frontiers of basic science.

Citation

Science

Volume

306

Pub Type

Journals

Download Paper

Local Download

Keywords

atomic clock, microwave and optical frequency standards, time standards

Citation

Diddams, S. , Bergquist, J. , Jefferts, S. and Oates, C. (2004), Standards of time and frequency at the outset of the 21st century, Science, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50063 (Accessed November 5, 2025)