A fundamental assumption about how to build a global "quantum internet" has just been overturned. Researchers at the University of Technology Sydney have shown through detailed modeling that quantum signals can feasibly be sent from Earth up to a satellite, an "uplink" direction long dismissed by scientists as impossible.
Until now, quantum satellites like China's Micius have worked exclusively on a "downlink" model: generating pairs of entangled photons in space and sending them down to separate ground stations to create ultra-secure encryption keys. The reverse process (creating entangled photons on Earth and firing them upward to meet at a fast-moving satellite) was considered impractical due to severe signal loss, atmospheric interference, and the immense precision required.
Surprisingly, the team's models, which accounted for real-world hurdles like background light and atmospheric distortion, indicate the feat is achievable. This paradigm shift offers major practical advantages. Ground stations can use more powerful, maintainable hardware to generate stronger signals, while the satellite only needs a compact optical unit to receive them, making it smaller, cheaper, and more power-efficient. This architecture is considered crucial for establishing the high-bandwidth links needed to network future quantum computers, forming the backbone of a true quantum internet.
The researchers suggest the concept could soon be tested using receivers on high-altitude drones or balloons, paving the way for a future where quantum entanglement is a ubiquitous utility, much like electricity.