The Quantum Theory of Measurement

Abstract

The purpose of measurements is the determination of properties of the physical system under investigation. In this sense the general conception of measurement is that of an unambiguous comparison: the object system S, prepared in a state T, is brought into a suitable contact — a measurement coupling — with another, independently prepared system, the measuring apparatus from which the result related to the measured observable E is determined by reading the value of the pointer observable. It is the goal of the quantum theory of measurement to investigate whether measuring processes, being physical processes, are the subject of quantum mechanics. This question, ultimately, is the question of the universality of quantum mechanics (see Chap. I).