Changes in electric-field noise due to thermal transformation of a surface ion trap

TL;DR

This study investigates how heat treatments alter the microscopic surface properties of metal ion traps, leading to increased electric-field noise, by combining ion trapping, surface analysis, and surface modification techniques.

Contribution

It provides new insights into the microscopic mechanisms behind thermal transformations and their impact on electric-field noise in surface ion traps.

Findings

Heat treatments increase electric-field noise levels.

Surface composition changes correlate with noise increase.

Contaminant deposition and atomic restructuring are key factors.

Abstract

We aim to illuminate how the microscopic properties of a metal surface map to its electric-field noise characteristics. In our system, prolonged heat treatments of a metal film can induce a rise in the magnitude of the electric-field noise generated by the surface of that film. We refer to this heat-induced rise in noise magnitude as a thermal transformation. The underlying physics of this thermal transformation process is explored through a series of heating, milling, and electron treatments performed on a single surface ion trap. Between these treatments, $^{40}$Ca$^+$ ions trapped 70~$\mu$m above the surface of the metal are used as detectors to monitor the electric-field noise at frequencies close to 1~MHz. An Auger spectrometer is used to track changes in the composition of the contaminated metal surface. With these tools we investigate contaminant deposition, chemical reactions, and atomic restructuring as possible drivers of thermal transformations.