  The quantum Brownian motion of a single neutral particle with nonzero
electric dipole moment placed in a photon gas at fixed temperature and close to
a conducting wall is here examined. The interaction of the particle with the
photon field leads to quantum dispersions of its linear and angular momenta,
whose magnitudes depend on the temperature, distance to the wall, and also on
the dipole moment characteristics. It is shown that for typical experimental
parameters the amount of energy held by the dipole rotation is expressively
larger than the one related to the center of mass translation. Furthermore, the
particle kinetic energy in presence of a thermal bath can decrease if the wall
is added to the system, representing a novel quantum cooling effect where the
work done by the quantum vacuum extracts energy from the particle. Finally,
possible observable consequences are discussed.
