  Electric-field noise from the surfaces of ion-trap electrodes couples to the
ion's charge causing heating of the ion's motional modes. This heating limits
the fidelity of quantum gates implemented in quantum information processing
experiments. The exact mechanism that gives rise to electric-field noise from
surfaces is not well-understood and remains an active area of research. In this
work, we detail experiments intended to measure ion motional heating rates with
exchangeable surfaces positioned in close proximity to the ion, as a sensor to
electric-field noise. We have prepared samples with various surface conditions,
characterized in situ with scanned probe microscopy and electron spectroscopy,
ranging in degrees of cleanliness and structural order. The heating-rate data,
however, show no significant differences between the disparate surfaces that
were probed. These results suggest that the driving mechanism for
electric-field noise from surfaces is due to more than just thermal excitations
alone.
