Spontaneous excitation of a static atom in a thermal bath in cosmic string spacetime

TL;DR

This paper investigates how a static atom's energy change rates in a thermal bath are affected by the presence of a cosmic string, revealing oscillatory behavior and polarization-dependent effects.

Contribution

It provides the first detailed analysis of atomic transition rates near a cosmic string, highlighting polarization and position effects on energy exchange in a thermal environment.

Findings

Transition rates oscillate with atom-string distance.

Atomic polarization determines transition likelihoods.

Atoms on the string exhibit boundary-like behavior similar to reflecting surfaces.

Abstract

We study the average rate of change of energy for a static atom immersed in a thermal bath of electromagnetic radiation in the cosmic string spacetime and separately calculate the contributions of thermal fluctuations and radiation reaction. We find that the transition rates are crucially dependent on the atom-string distance and polarization of the atom and they in general oscillate as the atom-string distance varies. Moreover, the atomic transition rates in the cosmic string spacetime can be larger or smaller than those in Minkowski spacetime contingent upon the atomic polarization and position. In particular, when located on the string, ground-state atoms can make a transition to excited states only if they are polarizable parallel to the string, whereas ground state atoms polarizable only perpendicular to the string are stable as if they were in a vacuum, even if they are immersed in a thermal bath. Our results suggest that the influence of a cosmic string is very similar to that of a reflecting boundary in Minkowski spacetime.