Extended Wigner function formalism for the spatial propagation of   particles with internal degrees of freedom
  An extended Wigner function formalism is introduced for describing the quantum dynamics of particles with internal degrees of freedom in the presence of spatially inhomogeneous fields. The approach is used for quantitative simulations of molecular beam experiments involving space-spin entanglement, such as the Stern-Gerlach and the Rabi experiment. The formalism allows a graphical visualization of entanglement and decoherence processes. 
Marcel Utz, Malcolm H Levitt, Nathan Cooper, and Hendrik Ulbricht
quant-ph physics.atm-clus physics.atom-ph physics.chem-ph