Researchers from QuTech, a collaboration between TU Delft and TNO, have a first time teleporting quantum information between two nodes that did not have a direct connection with each other. According to QuTech, this teleportation can in the long run form the ‘backbone’ of a super-secure quantum Internet.
“We have shown that we can gather everything to make it all work at the same time. Because you are dealing with things that have conflicting interests, so to speak. It is a blueprint of what becomes possible,” he said. Hans Beukers. one of the scientists who participated in the study.
Quantum computers reckon with quantum physics, the theory of the world on the smallest scale. Unlike bits in ordinary computers, quantum bits (qubits) can not only be 0 or 1, but also 0 and 1 at the same time. As a result, quantum computers can make calculations that are not possible with current supercomputers. Quantum computers can therefore contribute to all kinds of important research, such as new materials that can cause an energy revolution or medicines that are tailored to the individual.
Connecting quantum computers requires another form of internet, which uses an ‘entanglement’ between qubits. What you do with one qubit immediately affects the other, even though these qubits are very far apart.
Delft researchers ‘filtered’ three qubits to create a quantum network. Until now, this has only been possible between two points.
From Alice to Charlie
Alice, Bob and Charlie are what the researchers call the three notes. They used the entanglement to teleport information from Alice to Charlie and skipped the intermediate Bob.
Alice and Bob were connected via fiber, Bob and Charlie, but Alice and Charlie had no physical connection. Bob enabled the teleportation of information between Alice and Charlie by uniting two intricacies.
When measuring quantum states, the information is immediately lost. This also happens with a measurement at Charlie, but that information then immediately appears on Alice’s page. The Qubit is transmitted encrypted, where the measurement result of Charlie determines the key. Alice then performs the necessary quantum operation to decrypt the qubit.
Not to crack
One of the great promises of a quantum internet is communication that cannot be intercepted or intercepted. If someone tried it, the information would disappear instantly. Only the sender and recipient can access certain information.
“With today’s computers and the Internet, anything can be broken as long as you have a computer that is powerful enough. Mathematical security can be broken, physics cannot. It is inherently safe, it is unbreakable,” says Beukers. “With quantum internet, it gets noticed immediately if anyone fiddles with certain information.”
He gives the example of a government agency sending nuclear secrets to another government organization. “It may not be possible to crack a message like this now, but one wants that to still be the case in 30 years. It is the promise of quantum internet.”
In addition to secure communication, quantum internet could also offer more privacy, Beukers says. “Services then no longer need all kinds of information about you in order to recognize you and help you.”
There is still a lot of work to be done before quantum computers work together in an international network. “First, we need to take the technology out of the laboratory and make it more robust in the field.” According to the researchers, this was almost the maximum achievable with the design used. “To make it scalable, a different setup is needed. We are looking for other particles to create entanglements with. Experiments are underway, but it is still in its infancy.”
Research is also being done into using infrared light to make quantum internet possible via normal fiber optic cables. “We will probably be ten years later before there is a worldwide network of quantum computers.”