 Atom-field dressed state

A dressed state of an atom and its driving field. Within the rotating-wave approximation, the paired configurations $|e,n⟩$ and $|g,n+1⟩$ mix. A classical-drive rotating-frame Hamiltonian $H=\hslash (-\Delta {\sigma }_z+\Omega {\sigma }_x)/2$ has eigenvalues $\pm \hslash \sqrt{{\Delta }^2+{\Omega }^2}/2$. At resonance its eigenvectors are equal-weight combinations of the two bare configurations. Radiative transitions between neighboring manifolds explain the Mollow triplet.