Abstract

Laser-cooled, trapped Yb⁺ is a versatile candidate for future frequency standards, with potential clock transitions in the microwave, infrared and optical regions. Research at NPL has concentrated on possible optical standards offered by narrow linewidth S-D and S-F transitions in the blue region of the spectrum.¹ The partial term scheme for Yb⁺ is shown in Fig. 1. The ²Si_1/2–²F_7/2 octopole transition at 467 nm is expected to have an ultranarrow natural linewidth (<<1 Hz). Observation of this transition could lead to an extremely high Q-optical reference, with low magnetic field sensitivity in the odd isotope case.

© 1994 IEEE