Collapse of the wave packet without mixture

An explicit model of the quantum measurement process with determinstic dissipative dynamics is presented. The usual results of quantum mechanics are recovered, in complete compatibility with the realistic interpretation. The model exhibits the famous reduction of the wave packet and the occurrence of probability is explained as being due to a random correlation variable whose value is fixed at the very beginning of each of the individual processes. The way that the experimentalist observes the result has no effect on the final state of the system and, consequently, paradoxes like Schrödinger's cat or Wigner's friend are avoided.Partially supported by the Swiss National Science Foundation.