Lamb Shift of Unruh Detector Levels

TL;DR

This paper explores how the energy levels of an Unruh detector are shifted similarly to the Lamb shift in QED, affecting the detector's spectrum in curved spacetime, especially under high-energy conditions.

Contribution

It introduces the concept of a Lamb shift for Unruh detectors and analyzes its impact on energy spectra in curved backgrounds, providing new insights into quantum effects in curved spacetime.

Findings

Lamb shift significantly alters detector energy levels in curved spacetime.

In the ultraviolet domain, the Lamb shift dominates over thermal response.

Proposes a new expression for local virtual energy density for accelerated observers.

Abstract

We argue that the energy levels of an Unruh detector experience an effect similar to the Lamb shift in Quantum Electrodynamics. As a consequence, the spectrum of energy levels in a curved background is different from that in flat space. As examples, we consider a detector in an expanding Universe and in Rindler space, and for the latter case we suggest a new expression for the local virtual energy density seen by an accelerated observer. In the ultraviolet domain, that is when the space between the energy levels is larger than the Hubble rate or the acceleration of the detector, the Lamb shift quantitatively dominates over the thermal response rate.