Abstract

Quantum technologies are set to revolutionise society and quantum networking may enable or enhance new capabilities or applications by exploiting the properties of quantum entanglement for distributed quantum computing, sensing, positioning, navigation, timing, and secure communication. However, the fragility of quantum states is a barrier to long-distance links, exponential losses in optical fibres being a major limitation. Satellite quantum nodes are a promising avenue for overcoming range constraints of terrestrial quantum links with recent pioneering in-orbit demonstrations showing the feasibility of space-based quantum communication channels. However, many challenges still remain for the construction of an Earth-spanning quantum internet. Here, we provide an overview of world-wide activities to develop space quantum networks and illustrate a path ahead.