How they achieved this is by slowing down the speed of light from its typical speed of 300 million meters per second to a much more manageable 180kmph, and they did this using fiber optics which is a system that is currently in place around the world, thus making their findings even more applicable and viable.
To slow down the speed of light, the scientists grafted cesium atoms to the fibers which allowed it to slow light down. In fact they were also able to bring the light to a complete stop and restart it again, with the photons staying exactly the same which is apparently an important prerequisite for quantum communication.
According to Professor Arno Rauschenbeute, “Quantum physics allows us to create a connection between sender and receiver, which makes eavesdropping impossible. The fundamental laws of quantum physics make sure that no one can tap the connection without being noticed.” Of course when such a system will actually be implemented remains to be seen, but this research does bring us one step closer.