MINIMIZATION OF ION MICROMOTION IN A PAUL TRAP

Micromotion of ions in Paul traps has several adverse effects, includi ng alterations of atomic transition line shapes, significant second-or der Doppler shifts in high-accuracy studies, and limited confinement t ime in the absence of cooling. The ac electric field that causes the m icromotion may also induce significant Stark shifts in atomic transiti ons. We describe three methods of detecting micromotion. The first rel ies on the change of the average ion position as the trap potentials a re changed. The second monitors the amplitude of the sidebands of a na rrow atomic transition, caused by the first-order Doppler shift due to the micromotion. The last technique detects the Doppler shift induced modulation of the fluorescence rate of a broad atomic transition. We discuss the detection sensitivity of each method to Doppler and Stark shifts, and show experimental results using the last technique.