Quantum internet signals beamed between drones a kilometre apart
+ 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. It is also the first time that photon entanglement has been transmitted from one moving device to another.
The achievement marks an important step towards a quantum internet, says Siddarth Joshi at the University of Bristol, UK. He agrees that drones could become the final chain in links from one part of the world to another, such as from your local relay station to your home or vehicle. “You’re driving around in your car and you want to maintain secure quantum communications, so you have these drones flying around behind you,” he says.
+ A laser on board one of the 35-kilogram drones created a pair of entangled photons by splitting a single photon with a crystal. One photon was sent directly to a ground station and the other to a second drone a kilometre away via a relay drone.
+ Motorised devices on each drone moved to ensure that the receivers and transmitters always lined up, and photons were focused and steered through the relay drone by a short piece of fibre-optic cable. The state of each photon was measured at the ground station and the results proved that the photons remained entangled.
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