Ion-trap measurements of electric-field noise near surfaces

Abstract

Electric-field noise near surfaces is a common problem in diverse areas of physics, and a limiting factor for many precision measurements. There are multiple mechanisms by which such noise is generated, many of which are poorly understood. Laser-cooled, trapped ions provide one of the most sensitive systems to probe electric-field noise at MHz frequencies and over a distance range 30 − 3000 µm from the surface. Over recent years numerous experiments have reported spectral densities of electric-field noise inferred from ion heating-rate measurements and several different theoretical explanations for the observed noise characteristics have been proposed. This paper provides an extensive summary and critical review of electric-field noise measurements in ion traps, and compares these experimental findings with known and conjectured mechanisms for the origin of this noise. This reveals that the presence of multiple noise sources, as well as the different scalings added by geometrical considerations, complicate the interpretation of these results. It is thus the purpose of this review to assess which conclusions can be reasonably drawn from the existing data, and which important questions are still open. In so doing it provides a framework for future investigations of surface-noise processes.

Effects of electrode surface roughness on motional heating of trapped ions

“…We briefly review the well-studied model of ion-trap motional heating due to electric-field noise [2,11] in Sec. II A.…”

“…II A. This electric-field noise is assumed to arise from adsorbate dipole fluctuations [8,11] and we highlight the dominant factors that modulate its contribution to the electric-field-noise spectral density. The mechanism behind these dipole fluctuations is outlined in Sec.…”

“…We only consider better-understood physical adsorption of atoms [8,11], or adatoms, which results from a balance between the attractive van der Waals force and the repulsive atom-wall electron exchange interaction force [15].…”

“…It has been suggested that these transitions could be induced by vibrations of electrode atoms, resulting in fluctuations of the adatom-electrode interaction potential U (z) [8,11,13] driving a phonon-induced transition rate…”

A low-drift, low-noise, multichannel dc voltage source for segmented-electrode Paul traps

“…It quantifies the strength of the coupling between the isolated trapped ion and the environment and depends on numerous factors of a fundamental and technical nature. 9 A lower bound for the heating rate is given by fluctuating electric fields from thermal Johnson noise in the trap electrodes. Heating rates beyond the Johnson noise limit have been dubbed "anomalous" and their origin is still under investigation.…”