Interference terms in particle spin
In the double slit experiment there are interference terms which are responsible for the way in which particles appear on a screen (diffraction pattern). The density matrix for an electron with spin |+X> going into a stern Gerlach alligned in the z direction also has off diagonal terms which idicate interference.
Is it correct to think that these interference terms are responsible for the fact that some electrons end up going up and others down just as particles go above and below a datum line which extends from the middle of the double slits to the screen?
Many thanks for any replies.