A simple model of spontaneous emission

TL;DR

This paper introduces a simple, accessible model of spontaneous emission from a two-level atom interacting with a finite set of field states, exploring how irreversibility and emission duration depend on the number of states.

Contribution

The paper presents a minimalistic model demonstrating how spontaneous emission and irreversibility can arise with a finite environment, emphasizing the role of model details.

Findings

Increasing field states can lead to permanent emission depending on model specifics

Irreversibility emerges as the number of states grows

Mathematical tools are simplified for educational clarity

Abstract

We present a very simple model of a spontaneous emission from a two-level atom, interacting with a field of a finite number of states. Such a process is often said to occur because of the large number of equally-probable states of environment. We show that in our model increasing the number of field states may and may not cause a practically permanent emission, depending on the details of the model. We also describe how irreversibility emerges with growing number of states. Mathematical tools are reduced to a necessary minimum and hopefully can be well understood by undergraduate students.