Publication Date:
2013-01-12
Description:
Historically, time measurements have been based on oscillation frequencies in systems of particles, from the motion of celestial bodies to atomic transitions. Relativity and quantum mechanics show that even a single particle of mass m determines a Compton frequency omega(0) = mc(2)/[formula: see text] where c is the speed of light and [formula: see text] is Planck's constant h divided by 2pi. A clock referenced to omega(0) would enable high-precision mass measurements and a fundamental definition of the second. We demonstrate such a clock using an optical frequency comb to self-reference a Ramsey-Borde atom interferometer and synchronize an oscillator at a subharmonic of omega(0.) This directly demonstrates the connection between time and mass. It allows measurement of microscopic masses with 4 x 10(-9) accuracy in the proposed revision to SI units. Together with the Avogadro project, it yields calibrated kilograms.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lan, Shau-Yu -- Kuan, Pei-Chen -- Estey, Brian -- English, Damon -- Brown, Justin M -- Hohensee, Michael A -- Muller, Holger -- New York, N.Y. -- Science. 2013 Feb 1;339(6119):554-7. doi: 10.1126/science.1230767. Epub 2013 Jan 10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics, University of California-Berkeley, CA 94720, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23306441" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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