A team from Griffith’s Centre for Quantum Dynamics in Australia have demonstrated how to rigorously test if pairs of photons – particles of light – display Einstein’s “Spooky action at a distance”, even under adverse conditions that mimic those outside the lab.
Quantum nonlocality is important in the development of new global quantum information networks, which will have transmission security guaranteed by the laws of physics.
Photons can be used to form a quantum link between two locations by making a pair of photons that are “Entangled” – so that measuring one determines the properties of its twin – and then sending one along a communication channel.
Team leader Professor Geoff Pryde said a quantum link had to pass a demanding test that confirmed the presence of quantum nonlocality between particles at either end.
“As the length of quantum channel grows, less and less photons successfully pass through the link, because no material is perfectly transparent and absorption and scattering take their toll.”
Dr Morgan Weston, first author of the study, said they selected the few photons that survived the high-loss channel and teleported those lucky photons into another clean and efficient, quantum channel.
The team aims to integrate their method into quantum networks that are being developed by the Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, and test it in real-life conditions.