Researchers at QuTech, a collaboration between TU Delft and TNO, have a first with the teleportation of quantum information between two nodes that did not have a direct connection to each other. According to QuTech, in the long term, this teleportation could form the “backbone” of a super-secure quantum Internet.
“We have shown that we can bring everything together, so that everything works at the same time. Because you are dealing with things that have conflicting interests, so to speak. It is a model of what becomes possible,” says Hans Beukers, one of the scientists. who participated in the study.
Quantum computers calculate with quantum physics, the theory about the world on the smallest scale. Unlike the bits in ordinary computers, quantum bits (qubits) can be not only 0 or 1, but also 0 and 1 at the same time. As a result, quantum computers can do calculations that are not possible with current supercomputers. Therefore, quantum computers can 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 a different type of Internet, which uses an ‘entanglement’ between qubits. What you do to one qubit immediately affects the other, even if those qubits are very far apart.
The Delft researchers ‘intertwined’ three qubits to create a quantum network. Until now, that was only possible between two points.
From Alice to Charlie
Alice, Bob, and Charlie are what the researchers call the three nodes. They used the entanglement to teleport information from Alice to Charlie, skipping the Bob in between.
Alice and Bob were connected by fiber, as were Bob and Charlie, but Alice and Charlie had no physical connection. Bob enabled the teleportation of information between Alice and Charlie reconciling two entanglements.
When measuring quantum states, the information is immediately lost. This also happens with a measurement on Charlie, but that information immediately shows up on Alice’s side. The qubit is transferred encrypted and the result of Charlie’s measurement determines the key. Alice then performs the quantum operation necessary to crack the qubit.
One of the great promises of a quantum internet is communication that can’t be intercepted or intercepted. If someone were to try that, the information would instantly disappear. Only the sender and receiver can access certain information.
“With today’s computers and the Internet, anything can be cracked as long as you have a computer that’s powerful enough. Mathematical security can be broken, physical security can’t. It’s intrinsically secure, it’s unbreakable,” says Beukers. “With the quantum internet, you can tell immediately if someone is messing with certain information.”
He gives the example of a government agency sending nuclear secrets to another government organization. “It may not be possible to decipher a message like this now, but you want it to be that way 30 years from now. That’s the promise of the quantum internet.”
In addition to secure communication, the quantum Internet could also offer more privacy, says Beukers. “Services no longer need all kinds of information about you to be able to recognize you and help you.”
There is still a lot of work to be done before quantum computers will work together in an international network. “First we need to get the technology out of the lab and make it more robust in the field.” According to the researchers, this was about the most that could be achieved with the design used. “To make it scalable, a different setup is needed. We’re looking for other particles to create entanglements with. Experiments are underway, but it’s still in its infancy.”
Research is also being carried out on using infrared light to make quantum internet possible over normal fiber optic cables. “We will probably be ten years before there is a worldwide network of quantum computers.”