Ultra-precise measurement of optical frequency ratios

We developed a novel technique for frequency measurement and synthesis, based on the operation of a femtosecond comb generator as transfer oscillator. The technique can be used to measure frequency ratios of any optical signals throughout the visible and near-infrared part of the spectrum. Relative uncertainties of $10^{-18}$ for averaging times of 100 s are possible. Using a Nd:YAG laser in combination with a nonlinear crystal we measured the frequency ratio of the second harmonic $\nu_{SH}$ at 532 nm to the fundamental $\nu_0$ at 1064 nm, $\nu_{SH}/\nu_0 = 2.000 000 000 000 000 001 \times (1 \pm 7 \times 10^{-19})$.Comment: 4 pages, 4 figure

Basic Atomic Physics

Contains reports on five research projects.National Science Foundation Grant PHY 96-024740National Science Foundation Grant PHY 92-21489U.S. Navy - Office of Naval Research Contract N00014-96-1-0484Joint Services Electronics Program Grant DAAHO4-95-1-0038National Science Foundation Grant PHY95-14795U.S. Army Research Office Contract DAAHO4-94-G-0170U.S. Army Research Office Contract DAAG55-97-1-0236U.S. Army Research Office Contract DAAH04-95-1-0533U.S. Navy - Office of Naval Research Contract N00014-96-1-0432National Science Foundation Contract PHY92-22768David and Lucile Packard Foundation Grant 96-5158National Science Foundation Grant PHY 95-01984U.S. Army Research OfficeU.S. Navy - Office of Naval Research Contract N00014-96-1-0485AASERT N00014-94-1-080

Europäische Metrologie

PTB-Mitteilungen. Band 119 (2009), Heft 4, Seite 305 - 342. ISSN 0030-834X1.: Göbel, Ernst O.: Europäische Metrologie – Einführung 2.: Kühne, Michael und Wolfgang Schmid: EURAMET – „European Association of National Metrology Institutes“ 3.: Stenger, Jörn: Das europäische Metrologieforschungsprogramm EMRP 4.: Siegner, Uwe: Das Targetprogramm „Elektrizität und Magnetismus“ in iMERA-plus 5.: Bosse, Harald: iMERA-plus und das Targetprogramm „Dimensionelle Metrologie“ 6.: Koch, Hans: Das Targetprogramm „Metrologie für die Gesundheit“ in iMERA-plus 7.: Buck, Wolfgang: Das Targetprogramm „SI und Naturkonstanten“ im iMERA-plus-Rahmen 8.: Leitner, Arnold, Wolfgang Schmid und Leslie Pendrill: Weiterentwicklung der nationalen und regionalen metrologischen Infrastruktur in Europ