Is the decoherence of a system the result of its interaction with the environment?

TL;DR

This paper challenges the common belief that decoherence requires a large environment, demonstrating through a model analysis that it can occur with just a single environmental particle.

Contribution

It reveals that decoherence can happen with minimal environment size, countering the traditional view of large environment necessity.

Findings

Decoherence can occur with a single-particle environment.

Traditional models emphasizing large environments may overlook simpler mechanisms.

The analysis questions the assumption that environment size is crucial for decoherence.

Abstract

According to a usual reading, decoherence is a process resulting from the interaction between a small system and its large environment where information and energy are dissipated. The particular models treated in the literature on the subject reinforce this idea since, in general, the behavior of a particle immersed in a large "bath" composed by many particles is studied. The aim of this letter is to warn against this usual simplified reading. By means of the analysis of a well-known model, we will show that decoherence may occur in a system interacting with an environment consisting of only one particle.