Quantum internet signals beamed between drones a kilometre apart

Entangled photons have been sent between two drones hovering a kilometre apart, demonstrating technology that could form the building blocks of a quantum internet. When a pair of photons are quantum entangled, you can instantly deduce the state of one by measuring the other, regardless of the distance separating them. This phenomenon, which Albert Einstein dismissively called "spooky action at a distance", is the basis of quantum encryption – using entangled particles to ensure communications are secret. Quantum networks are far more secure than the existing internet because any attempt to eavesdrop changes the state of the photons, alerting the recipient to foul play. Entangled photons have been transported more than 1000 kilometres in tests between a satellite and ground stations before, but now Zhenda Xie at Nanjing University in China and his colleagues have shown that links can be made over shorter distances with relatively inexpensive hardware.