Ekkehard Peik
Optical frequency standards with trapped laser-cooled ions
Ekkehard Peik
Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
Optical frequency standards based on forbidden transitions of trapped and laser-cooled ions have now achieved significantly higher stability and greater accuracy than primary cesium clocks. We investigate an optical clock based on the 171Yb+ ion. This ions possesses two suitable reference transitions: the electric quadrupole transition S1/2 - D3/2 at 688 THz and the extremely narrow electric-octupole transition S1/2 - F7/2 at 642 THz. The ratio of these transition frequencies can be measured as a dimensionless number with a femtosecond laser frequency comb, allowing precise evaluation of systematic uncertainty contributions and a sensitive search for temporal variations of the fine structure constant. We are preparing nuclear laser spectroscopy of the 7.6 eV transition between the two lowest states of the
Th-229 nucleus with trapped Th ions. We have developed concepts for a highly accurate nuclear clock based on this transition and describe first steps towards the experimental realization.
