Hi I am a little confused regarding circular polarization. I have attached a figure in order to explain the situation I have been thinking of: It shows (to the left) how a magnetic field changes from being positive to being negative. The arrow indicates my quantization axis. To the right I have sketched the incoming EM-light, and the circle indicates that it is circularly polarized. The direction is such that it is σ- wrt. the quantization axis (the right hand rule). The main objective is that I want to drive the Δm=-1 (from J=0, m=0 to J=1, m=-1) transition of an atom moving from left ro right. But this is the part that is troubling me: Am I allowed to just define the quantization axis the way I have? With this definition, the only thing that changes is the magnetic dipole moment of the atom, and it goes from negative to positive. Am I right in all this? Thanks for any help in advance. Best, Niles.