The Lamb shift in de Sitter spacetime

TL;DR

This paper investigates the Lamb shift of atoms in de Sitter spacetime, revealing thermal effects analogous to a thermal bath and the influence of acceleration, highlighting the intrinsic thermal nature of de Sitter space.

Contribution

It provides a detailed analysis of the Lamb shift in de Sitter spacetime, connecting it to thermal effects and the Unruh effect, which was not previously explored in this context.

Findings

Lamb shift of freely-falling atoms mimics thermal bath effects at Gibbons-Hawking temperature.

Static atoms' Lamb shift combines effects of de Sitter thermal nature and Unruh effect.

Structural similarity between de Sitter Lamb shift and thermal Minkowski spacetime cases.

Abstract

We study the Lamb shift of both freely-falling and static two-level atoms in interaction with quantized conformally coupled massless scalar fields in the de Sitter-invariant vacuum. We find that the Lamb shifts of both freely-falling and static atoms are in structural similarity to that of an inertial atom immersed in a thermal bath in a Minkowski spacetime. For the freely-falling atom, the Lamb shift gets a correction as if it was immersed in a thermal bath at the Gibbons-Hawking temperature, thus revealing clearly the intrinsic thermal nature of de Sitter spacetime. For the static atom, the Lamb shift is affected by a combination of the effect of the intrinsic thermal nature of de Sitter spacetime and the Unruh effect associated with the inherent acceleration of the atom.