Amazing stuff! However, it still not a working real uplink!
"Quantum satellites currently beam entangled particles of light from space down to different ground stations for ultra-secure communications. New research shows it is also possible to send these signals upward, from Earth to a satellite; something once thought unfeasible.
This breakthrough overcomes significant barriers to current quantum satellite communications. Ground station transmitters can access more power, are easier to maintain and could generate far stronger signals, enabling future quantum computer networks using satellite relays. ...
China launched the Micius satellite in 2016, which enabled the first experiments with the transmission of quantum-encrypted information from space. In 2025, the Jinan-1 microsatellite extended this progress with a 12,900 km quantum link between China and South Africa. ...
a “downlink”, said Professor Solntsev. “It’s mostly used for cryptography, where only a few photons (particles of light) are needed to generate a secret key.” ...
“The idea is to fire two single particles of light from separate ground stations to a satellite orbiting 500 km above Earth, travelling at about 20,000 km per hour, so that they meet so perfectly as to undergo quantum interference. Is this even possible?” said Professor Devitt.
“Surprisingly, our modelling showed that an uplink is feasible. We included real-world effects such as background light from the earth and sunlight reflections from the Moon, atmospheric effects and the imperfect alignment of optical systems,” he said. ..."
From the abstract:
"Significant work has been done to develop quantum satellites, which generate entangled pairs in space and distribute them to ground stations separated some distance away.
The reverse “uplink” case, where pairs are generated on the ground and swapped on the satellite using an optical Bell measurement, has not been seriously considered due to a prevailing assumption that it is practically infeasible.
In this paper, we illustrate the feasibility of performing Discrete Variable photonic Bell measurements in space by conducting a detailed numerical analysis to estimate the channel efficiency and attainable pair fidelity for various satellite-station configurations.
Our model accounts for a wide range of physical effects such as atmospheric effects, stray photons, and mode mismatch.
Our findings show promise toward the feasibility of photonic Bell measurements in space, which motivates future research toward large-scale satellite-based uplink entanglement distribution."
Scientists reveal it is possible to beam up quantum signals (original news release) "New research shows it is feasible to send quantum signals from Earth to a satellite, paving the way for stronger quantum communication networks."
(Bottom) A schematic of the proposed uplink setup. ... (Top) The Bell-measurement apparatus inside the satellite.
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