Electric-field noise and carbon diffusion on Au(110)

The decoherence of trapped-ion quantum gates due to heating of their motional modes is a fundamen-tal science and engineering problem. This heating is attributed to electric-field noise arising from the trap-electrode surfaces. We have investigated the origin of this noise by focusing on the diffusion of carbon-containing adsorbates on the Au(110) surface. We show how the carbon adatom diffusion on the gold surface changes the energy landscape, and how the adatom dipole moment varies with the diffusive motion. A simple model for the diffusion noise, which varies quadratically with the variation of the dipole moment, predicts a noise spectrum, in accord with the measured values.