Relativistic Effects in Atom and Neutron Interferometry and the Differences Between Them

TL;DR

This paper compares relativistic effects in atom and neutron interferometers, revealing asymmetries and the conditions under which these effects are observable or cancel out, with implications for experimental setups.

Contribution

It identifies the differences in relativistic effect sensitivity between neutron and atom interferometers and discusses how laser frequency shifting influences these effects.

Findings

Neutron interferometers show non-relativistic residues of relativistic effects.

Atom interferometers can cancel out relativistic effects through laser chirping.

Laser frequency shifting effectively turns the laboratory into a free-fall system.

Abstract

In recent years there has been an enormous progress in matter wave interferometry. The Colella- Overhauser-Werner (COW) type of neutron interferometer and the Kasevich-Chu (K-C) atom interferometer, are the prototype of such devices and the issue of whether they are sensitive to relativistic effects has recently aroused much controversy. We examine the question of to what extent the gravitational red shift, and the related twin paradox effect can be seen in both of these atom and neutron interferometers. We point out an asymmetry between the two types of devices. Because of this, the non-vanishing, non-relativistic residue of both effects can be seen in the neutron interferometer, while in the K-C interferometer the effects cancel out, leaving no residue, although they could be present in other types of atom interferometers. Also, the necessary shifting of the laser frequency (chirping) in the atom interferometer effectively changes the laboratory into a free-fall system, which could be exploited for other experiments.