  We report the experimental characterization of axialization - a method of
reducing the magnetron motion of a small number of ions stored in a Penning
trap. This is an important step in the investigation of the suitability of
Penning traps for quantum information processing. The magnetron motion was
coupled to the laser-cooled modified cyclotron motion by the application of a
near-resonant oscillating quadrupole potential (the "axialization drive").
Measurement of cooling rates of the radial motions of the ions showed an
order-of-magnitude increase in the damping rate of the magnetron motion with
the axialization drive applied. The experimental results are in good
qualitative agreement with a recent theoretical study. In particular, a
classical avoided crossing was observed in the motional frequencies as the
axialization drive frequency was swept through the optimum value, proving that
axialization is indeed a resonant effect.
