It is a quantum leap of sorts: wireless quantum encryption over very long distances just got a step closer.
Quantum communication relies on sending entangled photons, each carrying a bit of information. It is secure because it will be obvious if anyone intercepts the photons, since doing so will disrupt the entanglement. Safely received bits are then used as a key to encrypt further communications.
The furthest a quantum key has been sent through free space is 144 kilometres (New Scientist, 9 June 2007, p 14). Achieving greater distances is tough because the atmosphere disturbs the photons’ delicate quantum…
