Logo of the Physikalisch-Technische Bundesanstalt

Time and frequency


The research and development tasks of the subject area "Time and Frequency" are mainly derived from the Units and Time Act:

  1. Realization of the unit of time and its dissemination inside and outside PTB: Operation of the primary fountain clocks CSF1 and CSF2, of the primary atomic clocks CS1 and CS2, and of a group of commercial atomic frequency standards

  2. Realization of the Atomic Time Scale UTC(PTB)

  3. Dissemination of the unit of time and of legal time via the long-wave transmitter DCF77, a telephone modem service and the Internet

  4. International satellite time comparisons with comparison uncertainties of better than 10–15/day, collaboration in the realization of the time system of the European Global Navigation Satellite Systems (GNSS) Galileo

  5. Development of optical clocks on the basis of a laser-cooled trapped ytterbium ion (171Yb+) and an aluminium ion (27Al+), of ultracold neutral strontium atoms (87Sr lattice clock), and on the basis of an optical nuclear transition in 229Th with respect to a future redefinition of the unit of time

  6. Development of methods for the optical frequency transmission via optical fibres and for a worldwide comparison of optical clocks which are very far apart.