Quantum coherence of photons at cosmological distances

TL;DR

This paper investigates potential sources of quantum decoherence for photons over cosmological distances, finding that interstellar medium interactions dominate and that quantum teleportation with keV photons could be feasible across vast cosmic scales.

Contribution

It provides a detailed analysis showing that cosmological effects like universe expansion and axion-like particles have negligible decoherence impact, highlighting the interstellar medium as the main factor.

Findings

Decoherence from universe expansion and axion-like particles is negligible.

Interstellar medium interactions are the primary decoherence source.

Quantum teleportation with keV photons is feasible up to high redshifts.

Abstract

We identify potential sources of decoherence for $U(1)$ gauge bosons from a cosmological standpoint. Besides interactions with different species in the cosmological medium, we also consider effects due to the expansion of the Universe, which can produce particles (especially scalars) than can potentially interact with the photon in a quantum state. We look in particular at the case of axion-like particles and their predicted decay channels in our analysis. These interactions are shown to have a negligible effect as far as decoherence goes. Interaction rates with CMB radiation or through Thomson scattering are small, so that the interstellar medium remains the biggest decoherence factor. Thus, quantum teleportation experiments with photon energies in the range $1$-$10$ keV should be feasible at cosmological distances up to the galaxy formation epoch or beyond ($z \sim 100$).