Quantifying Decoherence

TL;DR

This paper proposes a natural measure of quantum decoherence based on entanglement with environment degrees of freedom, demonstrating its effectiveness through example systems and a potential experimental setup.

Contribution

It introduces a simple, effective measure of decoherence rooted in entanglement, along with a method for experimental measurement in interferometry.

Findings

The measure effectively quantifies decoherence in various systems.

The proposed method is straightforward to compute.

A new experimental approach for measuring decoherence in neutron interferometry.

Abstract

Quantum decoherence refers to the phenomenon when the interaction of a quantum system with its environment results in the degradation of quantum coherence. Decoherence is considered to be the most popular mechanism responsible for the emergence of classicality from quantum mechanics. The issue of formulating a measure of decoherence is addressed here. The approach taken here is that decoherence results from the entanglement of a quantum system with certain environment degrees of freedom, and quantifying this entanglement should yield the most natural measure of decoherence. A simple measure of decoherence is presented based on this notion, and it is examined for various example systems. The measure proves to be effective and is relatively straightforward to compute. In addition, a method has been proposed to measure decoherence in a Mach-Zehnder interferometer which may be useful in neutron interferometry.