Radiative properties of a two-level atom in a moving causal permeable medium

A fully quantum-mechanical theory is presented for the interaction of quantized electromagnetic field with a two-level atom immersed in an isotropic moving causal permeable medium. The time dependence of the atom-field system is obtained in interaction picture. Special attention is paid to the decay rate and the quantum electrodynamics level shift of the atom. Due to the velocity of the medium, the atom experiences an anisotropic characteristic behavior from the background medium. To illuminate this effect, we calculate the torque experienced by a two-level atom.