Long-distance quantum communication can be achieved by directly sending light through space using a train of orbiting satellites that function as optical lenses.
Long-distance quantum communication can usher in hack-proof communication, enable precision quantum sensing technologies, and ultimately yield a quantum Internet. Existing protocols for global-scale quantum communication demand high-performance quantum memories, which have limited communication distance. This study proposes a chain of satellites in low Earth orbit to directly transmit photonic qubits through space, using the satellites like optical lenses to counter diffraction loss. Simulations and analysis of different quantum communication protocols using this relay system show the feasibility of building a global quantum network of only satellites, without requiring quantum memories.
Spooky Action at a Global Distance − Resource-Rate Analysis of a Space-Based Entanglement-Distribution Network for the Quantum Internet
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. These drawbacks prevent 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 determine the optimal resource cost of such a network for obtaining continuous global coverage. We also analyze the performance of the network in terms of achievable entanglement-distribution rates and compare these rates to those that can be obtained using ground-based quantum-repeater networks.