Emulation of satellite up-link quantum communication with entangled photons

TL;DR

This paper demonstrates the feasibility of satellite uplink quantum communication using entangled photons, showing secure key distribution over high-loss scenarios with terrestrial fiber links, supporting future low-Earth orbit satellite missions.

Contribution

It presents an ultra-bright entangled photon source and emulates satellite uplink conditions, validating the potential for secure quantum communication without trusted ground stations.

Findings

Achieved 5.2 kbit secure key in emulated high-loss satellite uplink scenario.

Confirmed the viability of satellite uplink quantum key distribution for future space missions.

Demonstrated compatibility with existing satellite and ground station technology.

Abstract

Quantum communication rates in terrestrial quantum networks are fundamentally limited by fibre loss, even in the presence of quantum repeaters. Satellites offer a solution for long-distance communication, with the most commonly explored scenario involving prepare-and-measure protocols connecting from orbit to a trusted-node ground station via free-space down-links. In contrast, up-link scenarios allow for entanglement to be distributed between a satellite and remote end users in terrestrial networks, eliminating any trust requirement on the ground station. Here we demonstrate an ultra-bright source of far-non-degenerate entangled photons and perform quantum key distribution in emulated high-loss satellite scenarios. With a loss profile corresponding to that of one of the pioneering Micius up-link experiments, and a terrestrial end user separated by 10~km of telecom fibre we achieve secure key bit accumulation of 5.2~kbit in a single emulated overpass in the asymptotic limit. Our results confirm the viability of upcoming low-Earth orbit receiver satellite missions.