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Panoramic view of the clock hall at PTB with the four caesium clocks CS1, CS2, CSF1 and CSF2.

What are the present fields of research of the working groups?

The newly developed atomic clock which is known as "caesium fountain" is much more accurate than atomic clocks of "classical" design. This is due to the use of laser-cooled caesium atoms which are catapulted 1 m upwards like a fountain. On a ballistic trajectory the rising and falling atoms cross a microwave field in which they are irradiated. As for the traditional atomic clocks, the relative number of atoms in the two hyperfine structure states changes depending on the frequency of the microwave field. As before, this change is measured and the microwave generator is stabilized to the atomic resonance.

Together with the improvement of the existing atomic clocks and the development of new ones, the development of the transmission of legal time is pursued.

More about PTB's research on clocks and time scales can be found on the web pages of the Time and Frequency Department.