Electric-field noise from thermally activated fluctuators in a surface ion trap

Abstract

We probe electric-field noise near the metal surface of an ion-trap chip in the temperature range from 295 to 530 K. We observe a nontrivial temperature dependence with the noise amplitude at 1 MHz frequency saturating around 500 K. Measurements of the noise spectrum reveal a $1/{f}^{\ensuremath{\alpha}\ensuremath{\approx}1}$ dependence and a small decrease in $\ensuremath{\alpha}$ between low and high temperatures. This behavior can be explained by considering noise from a distribution of thermally activated two-level fluctuators with activation energies between 0.35 and 0.65 eV. Processes in this energy range may be relevant to understanding electric-field noise in ion traps; for example, defect motion in the solid state and surface adsorbate binding energies. The study of these processes may aid in identification of the origin of excess electric-field noise in ion traps---a major source of ion motional decoherence limiting the performance of surface traps as quantum devices.