Probing Quantum Violations of the Equivalence Principle

TL;DR

This paper explores potential quantum violations of the equivalence principle, analyzing experimental data from neutron and atomic interferometry, and predicts future atomic experiments could detect such quantum effects.

Contribution

It provides a theoretical framework supporting quantum violations of the equivalence principle and predicts observable effects in next-generation atomic interferometry.

Findings

Neutron interferometry shows significant VEP indications.

Atomic interferometry results currently do not show VEP.

Future atomic experiments may detect quantum VEP effects.

Abstract

The joint realm of quantum mechanics and the general-relativistic description of gravitation is becoming increasingly accessible to terrestrial experiments and observations. In this essay we study the emerging indications of the violation of equivalence principle (VEP). While the solar neutrino anomaly may find its natural explanation in a VEP, the statistically significant discrepancy observed in the gravitationally induced phases of neutron interferometry seems to be the first indication of a VEP. However, such a view would seem immediately challenged by the atomic interferometry results. The latter experiments see no indications of VEP, in apparent contradiction to the neutron interferometry results. Here we present arguments that support the view that these, and related torsion pendulum experiments, probe different aspects of gravity; and that current experimental techniques, when coupled to the solar-neutrino data, may be able to explore quantum mechanically induced violations of the equivalence principle. We predict quantum violation of the equivalence principle (qVEP) for next generation of atomic interferometry experiments. The prediction entails comparing free fall of two different linear superpositions of Cesium atomic states.