Abstract

The use of the forbidden optical transition of a single laser-cooled ion stored in a Paul-Straubel trap has been proposed as the basis for a new atomic frequency standard of high accuracy.¹ We investigated the In⁺ ion with its narrow 5 s^{2 1}S₀ → 5 s 5p ³P₀ transition at 236.5nm² (Fig. 1). This clock transition is especially technically convenient, since it coincides with the fourth harmonic of the 946-nm transition ⁴F_3/2 → ⁴I_9/2 of the ND:YAG laser. So this intrinsically frequency stable solid-state laser can be used as the oscillator to drive the clock transition.³

© 1994 IEEE