Can spacetime curvature induced corrections to Lamb shift be observable?

TL;DR

This paper calculates how spacetime curvature near massive astrophysical objects significantly alters the Lamb shift, proposing potential observational detection of quantum effects through astronomical spectra.

Contribution

It introduces a method to compute curvature-induced Lamb shift corrections outside spherically symmetric bodies, highlighting their potential observability.

Findings

Corrections can reach ~25% near neutron stars and black holes.

Significant Lamb shift modifications occur at several gravitational radii.

Potential for astronomical detection of quantum spacetime effects.

Abstract

The Lamb shift results from the coupling of an atom to vacuum fluctuations of quantum fields, so corrections are expected to arise when the spacetime is curved since the vacuum fluctuations are modified by the presence of spacetime curvature. Here, we calculate the curvature-induced correction to the Lamb shift outside a spherically symmetric object and demonstrate that this correction can be remarkably significant outside a compact massive astrophysical body. For instance, for a neutron star or a stellar mass black hole, the correction is $\sim$ 25% at a radial distance of $4GM/c^2$, $\sim$ 16% at $10GM/c^2$ and as large as $\sim$ 1.6% even at $100GM/c^2$, where $M$ is the mass of the object, $G$ the Newtonian constant, and $c$ the speed of light. In principle, we can look at the spectra from a distant compact super-massive body to find such corrections. Therefore, our results suggest a possible way of detecting fundamental quantum effects in astronomical observations.