Control and measurement of electric dipole moments in levitated optomechanics

TL;DR

This paper demonstrates control over electric dipole moments in levitated optomechanical systems, significantly reducing background noise and improving precision sensing capabilities by measuring and canceling dipole-induced effects.

Contribution

It introduces a method to cancel dipole-induced backgrounds in levitated microspheres, enhancing control over their electric charge distribution.

Findings

Dipole moments scale with sphere size.

Induced dipoles are mainly due to dielectric-loss properties.

Background reduction by two orders of magnitude.

Abstract

Levitated optomechanical systems are rapidly becoming leading tools for precision sensing, enabling a high level of control over the sensor's center of mass motion, rotation and electric charge state. Higher-order multipole moments in the charge distribution, however, remain a major source of backgrounds. By applying controlled precessive torques to the dipole moment of a levitated microsphere in vacuum, we demonstrate cancellation of dipole-induced backgrounds by 2 orders of magnitude. We measure the dipole moments of ng-mass spheres and determine their scaling with sphere size, finding that the dominant torques arise from induced dipole moments related to dielectric-loss properties of the SiO$_2$ spheres. Control of multipole moments in the charge distribution of levitated sensors is a key requirement to sufficiently reduce background sources in future applications.