Dirac theory of ring-shaped electron distributions in atoms - art. no. 025404

The time-dependent Dirac equation is solved numerically on a space-time gri d for an atom in a strong static magnetic field and a laser field. The reso nantly induced relativistic motion of the atomic electron leads to a ringli ke spatial probability density similar to the features that have been recen tly predicted [Wagner, Su, and Grobe, Phys. Rev. Lett. 84, 3282 (2000)] bas ed on a phase-space method. We further demonstrate that spin-orbit coupling for a fast-moving electron in such an atom becomes significant and the tim e dependence of the spin can dephase even if initially aligned parallel to the direction of the static magnetic field.