title: Spin dynamics in the Kapitza-Dirac effect.
abstract: Electron spin dynamics in Kapitza-Dirac scattering from a standing laser wave of high frequency and high intensity is studied. We develop a fully relativistic quantum theory of the electron motion based on the time-dependent Dirac equation. Distinct spin dynamics, with Rabi oscillations and complete spin-flip transitions, is demonstrated for Kapitza-Dirac scattering involving three photons in a parameter regime accessible to future high-power x-ray laser sources. The Rabi frequency and, thus, the diffraction pattern is shown to depend crucially on the spin degree of freedom.
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Ahrens
authors.forename: Heiko
authors.initials: H
authors.lastname: Bauke
authors.forename: Christoph H
authors.initials: CH
authors.lastname: Keitel
authors.forename: Carsten
authors.initials: C
authors.lastname: Müller