Search for non-Newtonian interactions at micrometer scale with a levitated test mass

TL;DR

This study uses an optically levitated microsphere to search for non-Newtonian forces at micrometer scales, setting new constraints on hypothetical interactions and demonstrating a novel testing method with unique systematic considerations.

Contribution

It introduces a new optically levitated test mass technique for probing non-Newtonian forces at micrometer distances, expanding the experimental approaches in gravity research.

Findings

Set a constraint of ||  10^8 for  > 10 5m

Achieved force sensitivity of  10^{-16} N/ Hz

First inverse-square law test with an optically levitated test mass of similar size to 

Abstract

We report on a search for non-Newtonian forces that couple to mass, with a characteristic scale of ${\sim}10~\mu$m, using an optically levitated microsphere as a precision force sensor. A silica microsphere trapped in an upward-propagating, single-beam, optical tweezer is utilized to probe for interactions sourced from a nanofabricated attractor mass with a density modulation brought into close proximity to the microsphere and driven along the axis of periodic density in order to excite an oscillating response. We obtain force sensitivity of ${\lesssim}10^{-16}~\rm{N}/\sqrt{\rm{Hz}}$. Separately searching for attractive and repulsive forces results in the constraint on a new Yukawa interaction of $|\alpha| \gtrsim 10^8$ for $\lambda > 10~\mu$m. This is the first test of the inverse-square law using an optically levitated test mass of dimensions comparable to $\lambda$, a complementary method subject to a different set of systematic effects compared to more established techniques.