Spontaneous excitation of an accelerated atom: The contributions of vacuum fluctuations and radiation reaction

TL;DR

This paper analyzes how vacuum fluctuations and radiation reaction contribute to the spontaneous excitation of an accelerated atom, providing insights into the physical processes behind the Unruh effect.

Contribution

It quantitatively distinguishes the roles of vacuum fluctuations and radiation reaction in the spontaneous excitation of an accelerated atom, enhancing understanding of the Unruh effect.

Findings

Vacuum fluctuations significantly contribute to atomic excitation.

Radiation reaction influences the atom's energy variation.

The atom reaches equilibrium with the quantum field.

Abstract

We consider an atom in interaction with a massless scalar quantum field. We discuss the structure of the rate of variation of the atomic energy for an arbitrary stationary motion of the atom through the quantum vacuum. Our main intention is to identify and to analyze quantitatively the distinct contributions of vacuum fluctuations and radiation reaction to the spontaneous excitation of a uniformly accelerated atom in its ground state. This gives an understanding of the role of the different physical processes underlying the Unruh effect. The atom's evolution into equilibrium and the Einstein coefficients for spontaneous excitation and spontaneous emission are calculated.