Comment on: "Does an atom interferometer test the gravitational redshift at the Compton frequency?"

TL;DR

This paper critiques Wolf et al.'s 2011 analysis, arguing that atom interferometers are inherently tests of gravitational redshift, contrary to Wolf et al.'s claims that they only test the weak equivalence principle.

Contribution

It clarifies that atom interferometers directly test gravitational redshift regardless of formalism, correcting misapplications of Schiff's conjecture and previous analyses.

Findings

Atom interferometers are direct redshift tests in any formalism.

Wolf et al.'s analysis does not support their conclusion of 'no redshift effect'.

Misapplication of Schiff's conjecture leads to incorrect interpretation.

Abstract

We show that Wolf et al.'s 2011 analysis in Class. Quant. Grav. v28, 145017 does not support their conclusions, in particular that there is "no redshift effect" in atom interferometers except in inconsistent dual Lagrangian formalisms. Wolf et al. misapply both Schiff's conjecture and the results of their own analysis when they conclude that atom interferometers are tests of the weak equivalence principle which only become redshift tests if Schiff's conjecture is invalid. Atom interferometers are direct redshift tests in any formalism.