Quantum Communications via Satellite with Photon Subtraction

TL;DR

This paper investigates the optimal setup for photon subtraction in satellite-based quantum communication, finding that transmitter-side subtraction enhances continuous-variable quantum key distribution between ground stations and LEO satellites.

Contribution

It demonstrates that for satellite quantum communication, photon subtraction at the transmitter outperforms receiver-side subtraction, contrasting with fiber-based systems.

Findings

Transmitter-side photon subtraction improves QKD performance in satellite links.

Receiver-side subtraction is less effective for space-based quantum communication.

Results influence design choices for future space quantum networks.

Abstract

Non-Gaussian continuous-variable quantum states represent a pivotal resource in many quantum information protocols. Production of such states can occur through photonic subtraction process either at the transmitter side prior to sending a state through the channel, or at the receiver side on receipt of a state that has traversed the channel. In the context of quantum protocols implemented over communication channels to and from Low-Earth-Orbit (LEO) satellites it is unclear what photonic subtraction set-up will provide for the best performance. In this work we show that for a popular version of continuous-variable Quantum Key Distribution between terrestrial stations and LEO satellites, photon subtraction at the transmitter side is the preferred set-up. Such a result is opposite to that found for fiber-based implementations. Our results have implications for all future space-based missions that seek to take advantage of the opportunities offered by non-Gaussian quantum states.