Spooky action at a global distance: analysis of space-based entanglement distribution for the quantum internet

TL;DR

This paper proposes a satellite constellation-based global quantum internet, analyzing optimal configurations for continuous entanglement distribution and comparing satellite links with ground-based quantum repeaters.

Contribution

It introduces a method to optimize satellite configurations for global quantum internet and provides analysis of entanglement rates versus ground-based schemes.

Findings

Optimal satellite configurations for continuous coverage identified.

Satellite-to-ground entanglement rates analyzed and optimized.

Comparison shows satellite links can outperform ground-based repeaters in certain scenarios.

Abstract

Recent experimental breakthroughs in satellite quantum communications have opened up the possibility of creating a global quantum internet using satellite links. This approach appears to be particularly viable in the near term, due to the lower attenuation of optical signals from satellite to ground, and due to the currently short coherence times of quantum memories. The latter prevents ground-based entanglement distribution using atmospheric or optical-fiber links at high rates over long distances. In this work, we propose a global-scale quantum internet consisting of a constellation of orbiting satellites that provides a continuous, on-demand entanglement distribution service to ground stations. The satellites can also function as untrusted nodes for the purpose of long-distance quantum-key distribution. We develop a technique for determining optimal satellite configurations with continuous coverage that balances both the total number of satellites and entanglement-distribution rates. Using this technique, we determine various optimal satellite configurations for a polar-orbit constellation, and we analyze the resulting satellite-to-ground loss and achievable entanglement-distribution rates for multiple ground station configurations. We also provide a comparison between these entanglement-distribution rates and the rates of ground-based quantum repeater schemes. Overall, our work provides the theoretical tools and the experimental guidance needed to make a satellite-based global quantum internet a reality.