Scientists make major breakthrough in ‘quantum entanglement’ that could change how the internet works

Scientists have managed to entangle two "quantum memories" at a distant much bigger than ever before, a breakthrough that could one day change the way the internet works.

The discovery could be a major step towards a quantum internet, though only a very early one. Scientists hope it can allow for the development of entanglement over long-distances and a number of nodes, which will be required for such a network.

Researchers have long hoped to develop a quantum internet, creating a new kind of network that uses the unusual behaviour of the quantum world to transmit data with vastly improved speeds and security.

A quantum network runs on a similar idea to the traditional internet, allowing for the communication of large amounts of data across long distances. But it would do so using quantum bits, or qubits, between quantum processors – offering new kinds of possibilities in addition to the current classical internet.

But to do so they will need to be able to transmit particles that are entangled, the "spooky" phenomenon that allows particles to affect each other at great distances. In recent years, there have been breakthroughs in doing so – which have allowed researchers to transmit entangled particles through cables or using satellites – but they have all been limited by distance.

When quantum transmission is used over such a long distance, the distribution does not often succeed, because the transmissions get lost and so cannot communicate reliably.

Until now, the furthest scientists have been able to entangle quantum memories is 1.3 kilometres. That suggests there may be difficulties scaling up such a system to a scale that it can actually be used, such as transmitting data across a city.

In the new research, engineers were able to transmit entangled particles over a much greater distance of 50km. They did so using a specific quantum effect that allows transmission over a vastly improved length.

Such a distance could allow for long-distance transmission of the kind that could attach cities together and finally work towards the dream of a quantum internet, the researchers write in the new paper, published in Nature.

"Extending these experiments to nodes separated by much longer distances will enable us to perform advanced quantum information tasks, such as efficient quantum teleportation over long distances," they write in the paper.

In the study, researchers looked at how they could transmit two quantum memories, which are the quantum version of normal computer memory, or the equivalent of a hard drive. While a piece of computer memory will store information as 1s or 0s, the quantum memory will hold a quantum state, theoretically allowing for much more powerful computing.

To entangle those two quantum memories, researchers had to shoot photons, or individual particles of light, along the 50 kilometre cable. After making their way over that distance, the two memories were able to interfere with each other, making the experiment a success and demonstrating that two quantum memories could become entangled over such a distance.