Hannover 2010 – scientific programme

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SYLA: Symposium 50 Years of Lasers

SYLA 1: 50 Years of Lasers I

SYLA 1.3: Invited Talk

Wednesday, March 10, 2010, 15:00–15:30, E 415

Lasers for precision measurements — •Thomas Udem — Max-Planck-Institut für Quantenoptik

From the very beginning the laser was used as a valuable tool for research. A large amount of precision data about atoms and molecules has been obtained with narrow band single mode lasers. For the utmost precision frequency stabilization and counting techniques have been key ingredients. In 1983 the possibility to count optical cycles was used to re-define the meter in terms of the speed of light. The purpose was to remove an artefact from the SI units. Improved laser spectroscopic techniques have led to some of the best tests of quantum electrodynamics and the possibility to operate optical atomic clocks. These clocks are now taking over the lead as the most precise instruments enabling new tests of fundamental theories such as general relativity. As one of the latest developments lasers are getting used as calibration tools for precision astronomy and might help to find Earth-like extra solar planets. Eventually the precision might be sufficient to directly observe or rule out cosmic acceleration that is believed to be due to the prevalence of dark energy.