Search for new Interactions in a Microsphere Precision Levitation Experiment (SIMPLE):
The development of levitated optomechanics now allows particles with diameters between approximately 100 nm and 10 um to be trapped in optical traps operating in vacuum. By working in ultra high vacuum, thermal noise can be eliminated, so that the fundamental constraints on the sensitivity for measuring the motion of the particle arise from quantum mechanics itself (i.e., the measurement backaction of the readout laser used to determine the sphere position, as required by the Heisenberg uncertainty principle). Reaching the quantum measurement regime for these particles corresponds to extreme sensitivity to tiny forces (as small as 10-21 N) or accelerations (as small as 1 nano-g) acting on micron-scale objects.
The development of these precision sensors can enable a variety of new experiments aimed at understanding some of the major unanswered questions in particle and nuclear physics. We are currently applying these force sensors to the following experiments:
- Searches for dark matter particles scattering from trapped microspheres or nanospheres
- The most sensitive searches to date for “millicharged particles” (e.g., dark matter particles with charges that are much smaller than 1 electron charge) bound in matter
- Searches for sterile neutrinos or other neutral particles emitted in nuclear decays
- Tests of the inverse square law for gravity at distances as short as 1 micron
- Searches for new forces mediated by dark photons or other new, weakly coupled particles