Generating an Array of Levitated Microspheres and its Applications to Precision Searches for Dark Matter*

Optically levitated micron-sized spheres offer ~aN/√Hz force and ~ng/√Hz acceleration sensitivities for conducting precision measurements. The high mechanical, electrical and thermal isolation allows these force sensitivities, and has permitted ground state cooling for smaller nanometer sized objects. As such, levitated spheres have been utilized in millicharge particle searches, tests probing gravity at short ranges, and searches for impulses of imparted momentum from dark matter particles. Arrays of levitated microspheres can lead to improvements in many of these studies by increasing the mass available and filtering out background and noise via correlated motion of the spheres. Such arrays will be utilized to boost the cross section of dark matter scattering events and increase the sample size in millicharged particle searches. We present a system using an acousto-optic deflector to levitate a two dimensional array of microspheres in vacuum. This array is composed of time-shared traps with independent control of each sphere's position and feedback. We detail the methodology in creating, loading and monitoring an array, and we study optically and electrically mediated intersphere interactions to better understand backgrounds inherent with this new tool.