It is clear that photons will be the carrier of information in the quantum Internet, a network interconnected by quantum channels. However, until recently, the distance that photons could exceed has been limited by unavoidable losses when sent through free space or optical fibers. Recent milestone experiments establishing satellite-to-ground quantum communication have opened the way to truly large-distance quantum communication. Within this context, it is crucial to understand the properties of the satellite-based quantum network. Is this an efficient quantum network? Is it robust against failures?

By employing network theory, our main finding is to show that satellites can generate small-world quantum networks, implying that physically distant nodes are actually near from a network perspective. Furthermore, the existence of hubs—highly connected nodes—implies that this quantum network is robust against nodes and link failures. Altogether, our results establish satellite-based quantum communication as the most promising technology to distribute entanglement across large distances in quantum networks of growing size and complexity.

Our results provide a useful guide for the development of future quantum networks. However, they are only the first step toward more complicated and realistic models. For instance, it would be interesting to consider a nonuniform distribution of nodes that, for instance, simulates the fact that big cities typically have a greater concentration of nodes than rural areas. Another important line of research could be to study the quantum features of the transmitted photons, such as coherence and entanglement, and how these features impact the usefulness of the network for specific protocols.