Quantum satellites are used to send light particles from space to multiple ground stations to create ultra-secure communication links.
However, research conducted by a team of scientists from the University of Technology Sydney (UTS) has revealed that these light beams can also be sent from Earth to space.
Until now, quantum communication has been limited to downlinks. This method is secure and forms the basis of quantum-encrypted communications.
Tracking previous progress
China launched the Micius satellite in 2016, making its first major move in quantum communications. This move enabled landmark experiments in space-based quantum encryption.
In 2025, the progress continued with the Jinan-1 microsatellite establishing a 12,900-kilometer quantum link between China and South Africa, setting a new distance record.
“Current quantum satellites create entangled pairs in space and then send each half of the pair down to two places on Earth – called a ‘downlink’,” said Professor Alexander Solntsev, a member of the team.
“It’s mostly used for cryptography, where only a few photons (particles of light) are needed to generate a secret key,” he continued.
This breakthrough opens the door to building stronger, more flexible quantum communication networks, eventually creating a global quantum internet.
Reversing the flow
The idea of an uplink approach wasn’t on the agenda initially, with scientists thinking that it wouldn’t work due to signal loss, interference, and scattering. However, Professor Devitt and team demonstrated a method to show that the opposite approach is possible.
“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,” Professor Devitt explained.
“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.
According to researchers, the uplink concept could be used to build future quantum networks across different geographies using small low-orbit satellites.
The team incorporated real-world problems into their model, including background light from the Earth, reflections from the Moon, atmospheric effects, and slight misalignments in optical systems.
Despite these challenges, the model demonstrated that an uplink connection is feasible.
Building the quantum internet
“A quantum internet is a very different beast from current nascent cryptographic applications. It’s the same primary mechanism, but you need significantly more photons – more bandwidth – to connect quantum computers,” said Professor Devitt.
The uplink approach could deliver the high bandwidth needed for quantum networks because satellites would only require small optical units to process incoming photons, instead of carrying heavy quantum light-generating hardware.
This makes the system lighter, cheaper, and more practical. In the long term, the researchers believe quantum entanglement will become a basic utility, much like electricity, quietly powering devices and networks behind the scenes.