Einstein's 'spooky' theory and ultra-secure internet

Famed physicist Albert Einstein's scepticism about quantum mechanics could result in an ultra-secure internet, according to Chinese and Australian researchers.

Einstein's reservations about quantum mechanics were highlighted in a phenomenon known as 'spooky action at a distance'. In 1935, he highlighted a 'spooky' theory in quantum mechanics that is the strange way entangled particles stay connected even when separated by large distances.

But researchers QY He from Peking University in China and Margaret Reid from Swinburne University of Technology in Melbourne said that until now the real application of the theory had been for messages being shared between two people securely without interception, regardless of the spatial separation between them.

In a paper published in Physical Review Letters, the researchers provide theoretical proof that such messages could be shared between more than two people and might provide unprecedented security for a future quantum internet.

In the 1990s, scientists realised a message could be transmitted securely by encrypting and using a shared key generated by Einstein's strange entanglement to decode the message from the sender and receiver. Using the quantum key meant the message was completely secure from interception during transmission.

Sending Einstein's entanglement to a larger number of people would mean the key could be distributed among all the receiving parties, so they would have to collaborate to decipher the message. This would make the message even more secure.

"We found that a secure message can be shared by up to three to four people, opening the possibility to the theory being applicable to secure messages being sent from many to many," Reid said.

"The message will also remain secure even if the devices receiving the message have been tampered with, such as if an iPhone were hacked, because of the nature of Einstein's spooky entanglement."

Reid and He said discovering that this could be applied to a situation with more parties involved had the potential to create a more secure internet - with fewer messages being intercepted by external parties.