Technology
Quantum Key Distribution over Metropolitan Fiber Networks
Quick fact
In metropolitan fiber networks, QKD systems can deliver secure keys over distances of 50–100 km, but at 100 km, the signal becomes so weak that fewer than one photon in a billion sent by Alice reaches Bob, and the key rate drops to a few thousand bits per second.
Why this is interesting
You've probably shared a secret over the internet, but what if a hacker could intercept your message without you ever knowing? Quantum key distribution makes such spying impossible by using the weird rules of quantum physics.