Abstract

Trapping and cooling large numbers of ions, each confined to much less than an optical wavelength, is of great interest for high accuracy spectroscopy, improved frequency standards and atom-radiation field experiments. This can be achieved in a linear rf ion trap where the rf electric fields go to zero along a line rather than at only a point. As a step toward this goal we have constructed a linear trap and have observed simple crystallized linear structures of up to tens of ¹⁹⁹Hg⁺ ions. By varying the axial well depth (determined by a static potential) we have also observed more complex crystallized structures. The ion positions in these structures are in close agreement with a calculation that used as input the measured secular frequencies of the trap. We have also observed the 40.5-GHz ground-state hyperfine transition of trapped ¹⁹⁹Hg⁺ ions by microwave/optical double resonance.

© 1991 Optical Society of America