  Helium atoms in high- and low-field-seeking Rydberg states with linear and
quadratic Stark shifts have been confined in two dimensions and guided over a
distance of 150 mm using time-varying inhomogeneous electric fields. This was
achieved with an electrode structure composed of four parallel cylindrical rods
to which voltages were applied to form oscillating and rotating saddle-point
fields. These two modes of operation result in time-averaged pseudopotentials
that confine samples in high- and low-field-seeking states about the axis of
the device. The experimental data have been compared to the results of
numerical particle trajectory calculations that include effects of blackbody
radiation and electric field ionization. The results highlight important
contributions from single-photon blackbody-induced transitions that cause large
changes in the principal quantum number of the Rydberg atoms.
