Testing gravity at micron scales

Trapped Bead
Image of an optically levitated microsphere in vacuum.

How does gravity work at micron length scales?

Theories that attempt to unify gravity with the Standard Model or to explain the nature of dark energy suggest that gravity may deviate from the Newtonian form 1⁄r2 at micron length scales. We use mesoscopic optomechanical systems to measure sub-attonewton forces at micron length scales to test these theories. Our current work uses optically levitated microspheres to measure gravitational interactions between masses separated by less then 20 microns. Optically levitated microspheres provide a powerful probe for short-range forces because they can be precisely controlled with optics and do not need to be mechanically coupled to the surrounding environment. We are also exploring the use of mesoscopic optomechanical force sensors to search for other new particles and interactions. Recently, we have used optically levitated microspheres to search for millicharged particles (charged particles with much less than an electron's charge) bound in the bulk of the microspheres. Mesoscopic optomechanical systems are an important tool for probing new physics that may be most easily observed at the length scales between subatomic and laboratory length scales.



David C. Moore, Alexander D. Rider, and Giorgio Gratta. "Search for Millicharged Particles Using Optically Levitated Microspheres"
Phys. Rev. Lett. 113, 251801 (2014), doi:/10.1103/PhysRevLett.113.251801, PDF
Also see a short summary in APS Physics.
Alexander D. Rider, David C. Moore, Charles P. Blakemore, Maxime Louis, Marie Lu, and Giorgio Gratta. "Search for Screened Interactions Associated with Dark Energy below the 100 μm Length Scale"
Phys. Rev. Lett. 117, 101101 (2016), doi:/10.1103/PhysRevLett.117.101101, PDF
A.D. Rider et al. "Single-beam Dielectric Microsphere Trapping with Optical Heterodyne Detection"
Submitted to Phys. Rev. A., arXiv:1710.03558 [physics.ins-det], PDF


Poster at Particles and Nuclei International Conference (PANIC) 2014, Hamburg, Germany, Aug. 27, 2014
"Search for Millicharged Particles Using Optically Levitated Microspheres," Conference page, PDF

Back to Gratta Group main page

Site maintenance: Alex Rider.
Design: Giulio Gratta
Last modified: August 2014