QuTech researchers establish the first entanglement based quantum network

2024-01-17

A research team from QuTech, a Dutch quantum computing company, has just implemented a multi node quantum network consisting of three quantum processors and obtained a proof of principle for key quantum network protocols. In an article titled "Implementation of Multi node Quantum Networks Based on Remote Solid State Quantum Bits" recently published in the journal Science, they have introduced this important milestone discovery towards the future of quantum internet.

The strength of the Internet lies in its ability to connect any two computers on Earth, enabling new features that even applications designed decades ago could not dream of.

Nowadays, many laboratories around the world have researchers working hard to develop the first quantum internet. This network can connect any two quantum devices, such as quantum computers or sensors, at extremely distant distances.

Although today's internet still allocates information using the "1-bit" of 0 and 1, the future quantum internet will be able to use both states simultaneously.

One of the members of the research team, doctoral student Matteo Pompili, said, "From unbreakable communication, to cloud computing with complete user privacy, and to high-precision timing and other functions, quantum internet will open up a series of novel applications.".

In the past decade, researchers have managed to connect two quantum devices that share direct physical links together, thus taking the first step towards the quantum internet.

However, before implementing a scalable quantum network, it is still necessary to handle the transmission of quantum information through intermediate nodes, similar to routers in traditional internet.

At the same time, many promising quantum internet applications rely on entangled quantum bits, but they are often distributed between multiple nodes.

The so-called entanglement refers to a phenomenon observed at the quantum scale, which has been previously revealed by researchers to be able to achieve entanglement regardless of distance.

In addition to powerful quantum computers, this feature also lays the foundation for future quantum information sharing in the quantum internet.

In QuTech's experiment, the initial quantum network consists of three nodes located within the same building, with a certain distance between them. To enable these nodes to form a true network for operation, researchers have had to invent a novel architecture that extends beyond a single link.

It is reported that the intermediate node called Bob has physical connections with two external nodes called Alice and Charlie, allowing for the establishment of quantum entanglement links with each of these nodes.

In addition, Bob is equipped with an additional qubit that can be used as memory to store previously generated quantum links when establishing new ones.

After establishing quantum links between Alice Bob and Bob Charlie, Bob can convert these links into Alice Charlie's quantum links through a set of quantum operations.

An important feature of quantum internet is the need to declare the completion of these (essentially probabilistic) protocols through "flag" signals. Thiscrucial for the scalability of quantum networks, as many such protocols will be needed in the future to scale a large network.

Another member of the team, Sophie Hermans, stated, "Once a connection is established, we can maintain the final entangled state and protect it from noise interference. In theory, we can use these states for quantum key distribution, quantum computing, or any other subsequent quantum protocol.".

Research leader Ronald Hanson concluded, "Thisthe first entanglement based quantum network that can serve as a unique platform for researchers to develop and test the software, hardware, and protocols of quantum internet.".

The future quantum internet will be composed of countless quantum devices and intermediate nodes, and the QuTech team is studying the feasibility of providing compatibility with existing data infrastructure.

At the appropriate time, they will validate the current principles on telecommunications optical fibers outside the laboratory, and it is expected that QuTech's intercity quantum internet demonstration line will be completed by 2022.

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