My main interest in quantum measurement theory has been to investigate to what extent decoherence caused by interaction with the environment can mimic the collapse of the wave packet. In the first of the following papers it was shown that for any finite measurement there is a normal unitary evolution of the system interacting with the measuring apparatus and environment which gives, asymptotically the same effect as the von NeumannLueders projection. In the second it was shown that the normal model of light interacting with a polariser, using Maxwell's equations coupled to a dichroic material or reflecting at the Brewster angle from a dielectric, falls into precisely the class of models considered in the earlier paper. The third paper shows how microscopic atomic models can give exactly the macroscopic models used to describe the polarisers, and conversely how a discrete atomic model can be found to fit a given macroscopic model.



