March 31, 2008 Physicists at Padova University, Italy, are one step closer to constructing a quantum channel between space and Earth – the first step in establishing a truly secure quantum communications system. The Institute of Physics’ New Journal of Physics published the results of an experiment in which individual photons were reflected off a space satellite in orbit almost 1500 kilometers above the Earth, and identified back on the ground.

Since it’s impossible to observe interactions at a quantum level without affecting them, quantum communication is absolutely secure against eavesdroppers. Unfortunately, the small size of the particles also makes the communication hard to sustain beyond a distance of roughly 150 kilometers, due to photon scattering and absorption. By bouncing photons off the Japanese Ajisai Satellite, the scientists dramatically enhanced the scope of quantum communications – giving it wide potential for security agencies and communications companies all over the globe.

Paolo Villoresi and Cesare Barbieri wrote “We have achieved significant experimental results towards the realization of a quantum communication channel, as well as how to actually adapt an existing laser ranging facility for quantum communication.”

The next step is sending and receiving quantum keys, uncrackable strings of 1s and 0s that enable quantum communication from an active sender in space. The Italian Space Agency recently funded the initial phase of this project.