  Electric-field noise due to surfaces disturbs the motion of nearby trapped
ions, compromising the fidelity of gate operations that are the basis for
quantum computing algorithms. We present a method that predicts the effect of
dielectric materials on the ion's motion. Such dielectrics are integral
components of ion traps. Quantitative agreement is found between a model with
no free parameters and measurements of a trapped ion in proximity to dielectric
mirrors. We expect that this approach can be used to optimize the design of
ion-trap-based quantum computers and network nodes.
