Viability of quantum communication across interstellar distances

TL;DR

This paper explores the feasibility of quantum communication over interstellar distances, considering decoherence factors, suitable spectral bands, and the potential signals from extraterrestrial sources.

Contribution

It analyzes the impact of astrophysical and environmental factors on photon coherence and identifies the X-ray spectrum as the most promising for interstellar quantum communication.

Findings

X-ray spectrum is optimal for interstellar quantum communication

Decoherence factors include gravitational fields and interstellar medium particles

Challenges exist in detecting and interpreting extraterrestrial quantum signals

Abstract

The possibility of achieving quantum communication using photons across interstellar distances is examined. For this, different factors are considered that could induce decoherence of photons, including the gravitational field of astrophysical bodies, the particle content in the interstellar medium, and the more local environment of the Solar System. The X-ray region of the spectrum is identified as the prime candidate to establish a quantum communication channel, although the optical and microwave bands could also enable communication across large distances. Finally, we discuss what could be expected from a quantum signal emitted by an extraterrestrial civilization, as well as the challenges for the receiver end of the channel to identify and interpret such signals.