Wigner phase of photonic helicity states in the spacetime of the Earth

TL;DR

This paper investigates how Earth's gravitational field affects the quantum polarization states of photons traveling in curved spacetime, revealing a non-trivial Wigner phase even in static gravitational fields, with implications for quantum experiments.

Contribution

It demonstrates that photons acquire a non-trivial Wigner phase in static gravitational fields, challenging previous assumptions of trivial phases in such scenarios.

Findings

Photons in Earth's gravitational field gain a non-trivial Wigner phase.

The phase is present even in static spacetimes like Schwarzschild.

A gauge-invariant description of the phase remains an open problem.

Abstract

We study relativistic effects on polarised photons that travel in a curved spacetime. As a concrete application, we consider photons in the gravitational field of the Earth, on a closed path that starts at a terrestial laboratory, is reflected at one or more satellites, and finally returns to the laboratory. We find that the photons acquire a non-trivial Wigner phase already when the gravitational field is static, such as the Schwarzschild spacetime, where previous studies have found a trivial Wigner phase for closed photon paths. A gauge-invariant description of this nontrivial Wigner phase remains an open question, to be resolved before the formalism can provide predictions for experiments.