Particle physics research

New research could bring the quantum internet closer • The Register

Researchers in the Netherlands have shown they can transmit quantum information through an intermediary node, a feature needed to make the so-called quantum internet possible.

In recent years, scientists have argued that the quantum internet presents a more desirable network for transferring secure data, in addition to being necessary when connecting multiple quantum systems. All of this has attracted investment from the US government, among others.

Despite the promise, vital elements are still missing for the creation of a working quantum internet.

The transfer of quantum information – the superposition of states – between two network nodes becomes possible through the process of entanglement, which occurs when scientists create two or more particles such that the quantum state of each particle cannot not be described independently of the status of others. In this way, the researchers showed that they could “teleport” quantum information between two nodes.

Researchers from Qutech, a quantum computing research institute founded in 2014 by Delft University of Technology and the Netherlands Organization for Applied Scientific Research, have now demonstrated that they can create the effect via an intermediary node, a necessary condition for a functioning computer network.

As a learning aid in the otherwise hard-to-decipher field, PhD student Sophie Hermans and her colleagues named the network nodes with nicknames related to the infoseccers among us: Alice, Bob and Charlie. Alice and Charlie have no direct connection between them.

The researchers’ demonstration first creates entangled quantum states between neighboring nodes: Alice and Bob. The second node, or processor, then stores its entangled state. Next, Bob creates an entangled state with Charlie. Quantum scientists then exploited a particular effect known in their field. By measuring Bob’s condition, they affect the entanglement, creating a direct connection between Alice and Charlie.

The team then encoded the “message” information onto an additional qubit, which, when measured with Charlie’s entangled state, teleports the information to Alice, according to a paper in Nature this week.

While this is a significant demonstration of working concepts that may well become important in quantum networks, as with many in the field of quantum computing, practical applications are a long way off.

In an accompanying article, Oliver Slattery, Ph. ‘Korea Institute of Science and Technology, said the constant teleportation of information around a quantum network remained quite distant.

“Hermans et al. [have] managed to teleport quantum information between Alice and Charlie – two nodes with no direct connection. This achievement is not only a victory for basic science, but also represents a breakthrough in real-world problem solving needed to take this fascinating quantum application to the next level.

“Reliable teleportation around a quantum network is still a long way off, and this work clearly shows the enormous challenge ahead for the true realization of the quantum internet – but Hermans et al. offer a potential way forward. Increasing robustness memories used to preserve entanglement will lead to even higher entanglement rates, and an improved optical interface will increase the efficiency with which remote nodes are entangled,” they said.

a, Three network nodes, Alice (A), Bob (B) and Charlie (C).

Three network nodes, Alice (A), Bob (B) and Charlie (C), are connected by means of fiber optic links (lines) in an in-line configuration. Each configuration has a communication qubit (purple) that allows the generation of entanglement with its neighboring node

Nevertheless, the promise of moving quantum data securely over a network has such power that the US government is determined not to be left behind.

In 2020, the US Department of Energy presented a “model strategy” to develop a national quantum internet.

Energy Secretary Dan Brouillette said, “By building this new and emerging technology, the United States continues its commitment to maintaining and expanding our quantum capabilities.”

The U.S. government statement at the time said the quantum internet “could become a secure communications network and have a profound impact on areas critical to science, industry, and national security.” ®