Journal of the Physical Society of Japan
Asymmetrical Recoil of an Atom with an Optical Absorption Coefficient Depending on the Incident Direction
Norio Inui
Abstract
The recoil of a neutral atom irradiated by counter-propagating light with the same frequency and intensity is studied. The expectation value of the momentum transferred from the light to the atom with spherical symmetry at rest is usually zero because of symmetry. However, if the optical absorption coefficient of the atom depends on the incident light direction due to the magnetoelectric effect, as is the case in materials with nonreciprocal directional dichroism, the momentum transfer between the atom and photons depends on the incident direction. This allows even a standing electromagnetic wave to break the symmetry of the recoil of an atom.