  We theoretically show that the dipole force of an ensemble of quantum
emitters embedded in a dielectric nanosphere can be exploited to achieve
near-field optical levitation. The key ingredient is that the polarizability
from the ensemble of embedded quantum emitters can be larger than the bulk
polarizability of the sphere, thereby enabling the use of repulsive optical
potentials and consequently the levitation using optical near-fields. In
levitated cavity quantum optomechanics, this could be used to boost the
single-photon coupling by combining larger polarizability to mass ratio, larger
field gradients, and smaller cavity volumes while remaining in the resolved
sideband regime and at room temperature. A case study is done with a
nanodiamond containing a high-density of silicon-vacancy color centers that is
optically levitated in the evanescent field of a tappered nano-fiber and
coupled to a high-finesse microsphere cavity.
