On the Evolution of States in a Quantum-Mechanical Model of Experiments

TL;DR

This paper critically examines measurement postulates in quantum mechanics through a simple model, highlighting the need for principles governing the stochastic evolution of states to address the measurement problem.

Contribution

It analyzes a specific quantum measurement model and discusses the necessity of general principles for the stochastic evolution of states in quantum systems.

Findings

Critiques of von Neumann and Lüders measurement postulates

Identification of mathematical issues in Gisin's model

Emphasis on the need for principles governing stochastic state evolution

Abstract

The postulates of von Neumann and L\"uders concerning measurements in quantum mechanics are discussed and criticized in the context of a simple model proposed by Gisin. The main purpose of our paper is to analyze some mathematical aspects of that model and to draw some general lessons on the so-called ``measurement problem'' in quantum mechanics pointing towards the need to introduce general principles that determine the law for the stochastic time evolution of states of individual physical systems.