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Clocks for Length and Time Measurement

  • Fritz Riehle
Conference paper
  • 728 Downloads
Part of the Lecture Notes in Physics book series (LNP, volume 562)

Abstract

The evolution of various fields of science, technology, trade or legal metrology is intimately connected with the ability to relate measurements with each other that were performed at different places and different instants of time. For this purpose a practical system of units of measurement i.e. the International System of Units (SI) has been established by international cooperation [1]. In this SI, the metre and the second represent the base units of length and time, respectively. From all units these two can be realized with by far the highest accuracy since they are based on frequency measurements and most accurate clocks. In contrast to clocks based on mechanical properties of macroscopic bodies, e.g., pendulum clocks, quartz clocks or pulsars, the frequency reference for a suitable oscillator in atomic clocks is mainly determined by the intrinsic properties of suitable absorbers like atoms, molecules or ions. These atomic properties are determined by fundamental constants resulting from the basic interactions between the elementary constituents of matter. Following the generally accepted idea that the properties of each atomic absorber of a selected species are the same, identical clocks can be set up in any desired number and at any desired place.

Keywords

Frequency Standard Laser Cool Atomic Clock Paul Trap Optical Clock 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2001

Authors and Affiliations

  • Fritz Riehle
    • 1
  1. 1.Physikalisch-Technische Bundesanstalt (PTB)BraunschweigGermany

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