Quantum theory of statistical radiation pressure in free space

Light is known to exert radiation pressure on any surface it incident upon, via the transfer of momentum from light surface. In general, this force assumed be pushing or repulsive in nature. paper, we present a quantum treatment pressure. We show that interaction an atom with can lead both and attractive forces due absorption emission photons, respectively. An prepared excited state initially will experience pulling when interacting light. On other hand, if ground then repulsive, while having same magnitude as earlier case. Therefore, for ensemble atoms, direction net decided by populations. semi-classical light-matter processes have probability, therefore magnitudes two turn out same. obtain effective profile electromagnetic field, treatment, despite these probabilities being different, statistical remain This explained noting extra contribution process vacuum modes results symmetric profile, contributing zero atoms ensemble. further identify set states field which give rise non-zero atom.