  Levitated nano-spheres of silica, optically trapped in a Fabry-Perot cavity
with a single trapping field and the electrostatic field of a charged ring
electrode, are used to infer the potential existence of dark matter particles
with infinitesimal charge. These particles are presumed to exist in bulk matter
as relics of the primordial Universe. In the absence of infinitesimally charged
particles within the chosen nano-sphere, the output light in this setup should
be thermal. However, if these particles do exist, the cavity's output light is
expected to be squeezed even at room temperature, and one could observe
entanglement between light and the nano-sphere's center of mass.
