Optical Levitation of Arrays of Microspheres

TL;DR

This paper demonstrates techniques for trapping and controlling large two-dimensional arrays of microspheres in vacuum, enabling high-precision sensing and potential applications in fundamental physics research.

Contribution

It introduces methods for creating defect-free arrays of over 25 microspheres with independent optical control and high-sensitivity imaging.

Findings

Successfully trapped and controlled 25+ microspheres in vacuum

Achieved sub-nanometer displacement sensitivity for all spheres

Demonstrated imaging of entire array motion simultaneously

Abstract

Levitated optomechanical systems are rapidly becoming leading tools for precision sensing of forces and accelerations acting on particles in the femtogram to nanogram mass range. These systems enable a high level of control over the sensor's center-of-mass motion, rotational degrees of freedom, and electric charge state. For many sensing applications, extending these techniques to arrays of sensors enables rejection of correlated noise sources and increases sensitivity to interactions that may be too rare or weak to detect with a single particle. Here we present techniques capable of trapping defect free, two-dimensional arrays of more than 25 microspheres in vacuum. These techniques provide independent control of the optical potential for each sphere. Simultaneous imaging of the motion of all spheres in the array is demonstrated using camera-based imaging, with optimized object tracking algorithms reaching a displacement sensitivity below 1 nm/$\surd$Hz. Such arrays of levitated microspheres may find applications ranging from inertial sensing to searches for weakly interacting particles such as dark matter.