A microscopic model of electronic field noise heating in ion traps

TL;DR

This paper presents a microscopic theoretical model explaining electric field noise in ion traps, attributing it to adsorbed atoms' fluctuating dipoles, and matches experimental dependencies on distance, frequency, and temperature.

Contribution

It introduces a comprehensive model incorporating vibrational states of adsorbed atoms to explain electric field noise, extending beyond standard two-level fluctuator models.

Findings

Noise spectrum begins near the fundamental phonon transition frequency.

Electric field noise exhibits a $d^{-4}$ dependence on ion-electrode distance.

The model accounts for the observed frequency, temperature, and distance dependencies of heating rates.

Abstract

Motional heating of ions in micro-fabricated traps is a challenge hindering experimental realization of large-scale quantum processing devices. Recently a series of measurements of the heating rates in surface-electrode ion traps characterized their frequency, distance, and temperature dependencies, but our understanding of the microscopic origin of this noise is still vague. In this work we develop a theoretical model for the electric field noise which is associated with a random distribution of adsorbed atoms on the trap electrode surface. By using first principle calculations of the fluctuating dipole moments of the adsorbed atoms we evaluate the distance, frequency and temperature dependence of the resulting electric field fluctuation spectrum.Our theory calculates the noise spectrum beyond the standard scenario of two-level fluctuators, by incorporating all the relevant vibrational states. The $1/f$ noise is shown to commence at roughly the frequency of the fundamental phonon transition rate and the $d^{-4}$ dependence with distance of the ion from the electrode surface is established.