On unitary evolution and collapse in Quantum Mechanics

TL;DR

This paper discusses the differences between unitary evolution and wave function collapse in quantum mechanics, illustrating concepts with experiments like the Elitzur-Vaidman bomb and proposing new experiments to visualize decoherence.

Contribution

It provides a clear pedagogical comparison of quantum evolution and collapse, and proposes simple experiments to test decoherence and entanglement effects.

Findings

Distinction between unitary evolution and collapse clarified

Proposed experiments to visualize decoherence

Analysis of delayed choice and bomb experiments

Abstract

In the framework of an interference setup in which only two outcomes are possible (such as in the case of a Mach-Zehnder interferometer), we discuss in a simple and pedagogical way the difference between a standard, unitary quantum mechanical evolution and the existence of a real collapse of the wave function. Moreover, we also present the Elitzur-Vaidman bomb, the delayed choice experiment, and the effect of decoherence. In the end, we propose two simple experiments to visualize decoherence and to test the role of an entagled particle.