Quantum Satellites Topologies and Design Considerations

This white paper examines the design considerations and trade-offs associated with the implementation of quantum satellite systems, which are essential for enabling long-range quantum communication links necessary for expanding quantum networks. The document discusses various satellite-based quantum key distribution (QKD) architectures, including prepare-and-measure and entanglement-based protocols, which influence the topology and architecture of networks. Additionally, it addresses hybrid terrestrial-space quantum networks that leverage free-space links at varying altitudes, highlighting the importance of satellite-to-satellite connectivity. A detailed analysis of the considerations for satellite design is included, covering factors such as orbit selection, QKD protocol choice, quantum link direction, and wavelength selection. Each design element is crucial for achieving the necessary performance and scalability in quantum communication. The paper also presents advancements in intra-satellite technologies that pave the way for a hybrid terrestrial-space Quantum Internet.