Towards Precision Measurment of Gravity at Short Ranges with Optically Levitated Nanoparticles

Levitated optomechanical systems show great promise for precision measurement

experiments due to their extreme decoupling from the environment. Using these systems, we

can build ultrasensitive force sensors allowing for the study of weak forces such as gravity at

previously unexplored short distances. We show that by approaching with a conducting surface

directly in the beam path of the optical tweezer trap, we are able to create a standing wave

potential that the particle transitions into. This method gives extraordinary control over the

position of the particle in relation to the surface, while simultaneously mitigating the effects of

various noise sources. With the addition of feedback cooling of the center of mass motion of the

particle, we can ensure that the particle remains trapped in this configuration in high vacuum for

a sufficient amount of time. This ultrasensitive instrument capable of zeptonewton (10^-21N)

level force sensing is the platform in which we will use to study possible deviations from

Newton’s gravitational inverse square law. Additionally, this shows a promising step towards

constructing a macroscopic matter wave interferometer that may prove itself to be

advantageous over atom interferometers when measuring Newtonian gravity and other short

range forces near a surface.