Gravitationally induced phase shift on a single photon

TL;DR

This paper proposes a feasible optical fiber interferometry scheme to measure the gravitationally induced phase shift on a single photon, enabling tests of quantum-gravity interactions and photon mass equivalence.

Contribution

It introduces a novel interferometric method using a modified Mach-Zehnder setup to detect gravitational phase shifts on single photons.

Findings

Predicted phase shift of 10^{-5} radians is measurable with stabilization.

Fiber noise can be mitigated with stabilization techniques.

Method enables testing of photon gravitational mass equivalence.

Abstract

The effect of the Earth's gravitational potential on a quantum wave function has only been observed for massive particles. In this paper we present a scheme to measure a gravitationally induced phase shift on a single photon travelling in a coherent superposition along different paths of an optical fiber interferometer. To create a measurable signal for the interaction between the static gravitational potential and the wave function of the photon, we propose a variant of a conventional Mach-Zehnder interferometer. We show that the predicted relative phase difference of $10^{-5}$ radians is measurable even in the presence of fiber noise, provided additional stabilization techniques are implemented for each arm of a large-scale fiber interferometer. Effects arising from the rotation of the Earth and the material properties of the fibers are analysed. We conclude that optical fiber interferometry is a feasible way to measure the gravitationally induced phase shift on a single-photon wave function, and thus provides a means to corroborate the equivalence of the energy of the photon and its effective gravitational mass.