Recent results on the 688 THz Yb+ single-ion optical frequency standard are presented. The relative uncertainty of absolute frequency measurements of the standard was reduced to 2.0×10−15. We prepare to observe the electric-octupole transition of Yb+ at 642 THz with sub-hertz resolution. Measurements of the frequency ratio between the 688 THz and 642 THz transitions in Yb+ will permit to search for temporal variations of the fine structure constant.
© 2007 Optical Society of AmericaPDF Article