Advanced models for the Stern-Gerlach experiment

[A. Neumaier]

i cannot find much advanced stuff on Stern-Gerlach. The basic modelling of the experiment in QM you were referring to is in itself pretty simple and i do understand it. And I also understand how the resulting superposition of spin up/down states maps to the experimental outcome using the classic QM interpretation/measurement mechanics. [...]
But when it comes to talking about the collapse of the wave function this simplistic handling is at the range of validity. To begin within that framework the measurement is not well defined from a mathematical perspective – or at least I couldn’t find any strict axiom set from which one could derive that the measurement (or rather collapse or equivalent) does or does not happen directly at the SG device (please correct me if I’m wrong).

A detailed discussion of measurement in the Stern-Gerlach experiment can be given in the POVM setting; see this post.