  We propose to introduce additional control in levitated optomechanics by
trapping a meta-atom, i.e. a subwavelength and high-permittivity dielectric
particle supporting Mie resonances. In particular, we theoretically demonstrate
that optical levitation and center-of-mass ground-state cooling of silicon
nanoparticles in vacuum is not only experimentally feasible but it offers
enhanced performance over widely used silica particles, in terms of both trap
frequency and trap depth. Moreover, we show that, by adjusting the detuning of
the trapping laser with respect to the particle's resonance, the sign of the
polarizability becomes negative, enabling levitation in the minimum of laser
intensity e.g. at the nodes of a standing wave. The latter opens the door to
trapping nanoparticles in the optical near-field combining red and blue-detuned
frequencies, in analogy to two-level atoms, which is of interest for generating
strong coupling to photonic nanostructures and short-distance force sensing.
