The concept of quantum communications is not within the realms of pure sci-fi and new research from Italy takes practical results from the last few years to a new level.

Researchers in Italy have demonstrated the feasibility of quantum communications between high-orbiting global navigation satellites and a ground station, with an exchange at the single photon level over a distance of 20,000 km.

The milestone experiment proves the feasibility of secure quantum communications on a global scale, using the Global Navigation Satellite System (GNSS). The study and findings have been reported in full in the journal Quantum Science and Technology.

According to the study, space quantum communications (QC) represent a promising way to guarantee unconditional security for satellite-to-ground and inter-satellite optical links, by using quantum information protocols as quantum key distribution (QKD).

The team’s results show the first exchange of a few photons per pulse between two different satellites in the Russian GLONASS constellation and the Space Geodesy Centre of the Italian Space Agency. The single photon exchange with a GNSS satellite is seen as an important result for both scientific and application perspectives.

Co-lead author Professor Paolo Villoresi from the University of Padova said: “Our experiment used the passive retro-reflectors mounted on the satellites. By estimating the actual losses of the channel, we can evaluate the characteristics of both a dedicated quantum payload and a receiving ground station.

“QC could also offer interesting solutions for GNSS security for both satellite-to-ground and inter-satellite links, which could provide novel and unconditionally secure protocols for the authentication, integrity and confidentiality of exchanged signals.”

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