New Era in Quantum Communication: Proved that Photons Can Be Sent from Earth to Orbit

Metaverse Planet November 11, 2025Last Updated: November 11, 2025

2 minutes read

It has been proven for the first time that quantum satellites, which until now could only operate in a unidirectional manner, can operate bidirectionally. It is possible to send photons from Earth to orbit and deliver them to their target.

In the field of quantum communication, there has been unidirectional traffic until now. Quantum satellites in orbit send light particles (photons) from space to Earth; this method, known as “downlink,” forms the basis of quantum encryption technologies. However, this traffic may become bidirectional in the near future. A new study conducted by researchers at the University of Technology Sydney has revealed that establishing an “uplink” connection with quantum satellites—that is, sending photons from Earth to space and delivering them to their target—is theoretically possible. This development represents a significant first step for the quantum internet, which has the potential to be the communication infrastructure of the future.

Looking at the history of quantum satellites, China’s Micius satellite, launched in 2016, was the groundbreaking first step in this field. Thanks to Micius, space-based quantum encryption systems were tested, and the first secure connection was established from space to Earth. By 2025, the Jinan-1 microsatellite, also developed by China, expanded the boundaries of this field by establishing a record quantum link of 12,900 kilometers between China and South Africa. However, all these experiments were based on the downlink principle. The satellites sent entangled photon pairs, created in space, to two different ground stations, thus obtaining a common quantum key at two points.

Theoretically Possible to Deliver Photons to a Satellite Moving at 20,000 km/h

The study conducted at the University of Technology Sydney reverses this process. In this theoretical work, the team aimed to have single photons, launched simultaneously from two different ground stations, precisely meet on a satellite moving at a speed of 20,000 kilometers per second at 500 kilometers above the Earth. This scenario was largely considered unimplementable until now because it requires precision timing and pointing sensitive enough for the photons to form a quantum interference with each other. It was thought that light scattering in the atmosphere, signal losses, and background glare from Earth would make such a connection impossible. However, the modeling performed by Professor Simon Devitt and his team showed that the uplink connection is theoretically possible even when all these factors are taken into account.

Professor Devitt shared the promising results of the study, saying, “We included real-world conditions in our model, such as atmospheric effects, sunlight reflecting off the Moon, and minor misalignments of optical systems. Despite this, the results showed that the uplink connection is feasible.”

According to the researchers, uplink-based systems could play a crucial role in building global quantum communication networks in the long term. However, there are still serious engineering and physical limitations that need to be overcome for this to happen. Current quantum cryptography systems are limited to generating a “secret key” using only a few photons. A true quantum internet, however, requires much higher bandwidth and stability. The uplink approach could theoretically provide flexibility in this direction, because if an uplink connection is possible, satellites will no longer need to carry complex and heavy quantum light sources internally. Instead, smaller and simpler optical modules that can detect and process photons sent from Earth stations may suffice. Still, implementing these systems on a practical scale may take quite some time. The Sydney team is quite hopeful about this. According to them, in the future, quantum entanglement will become an invisible infrastructure, much like today’s electricity or internet, working silently in the background of devices and networks.