Breakthrough in quantum networks: three remote atomic qubits entangled for the first time
The world of quantum computing is taking another significant step forward. I have learned of a result that can confidently be called historic for the development of distributed quantum systems. A research group, combining efforts from academic science and the private sector, has successfully implemented three-way quantum entanglement between three spatially separated atomic qubits.
In the experiment, scientists managed to create the so-called Greenberger-Horne-Zeilinger (GHZ) state — a classic example of multipartite quantum entanglement. The key difference of this work from previous achievements is that, for the first time, such a state was formed on a platform of individual atomic qubits connected by photonic communication channels. Previously, similar networks were demonstrated on other physical platforms or only for two nodes.
Why this changes the game
The main problem with modern quantum computers is scaling. Creating one huge, error-free quantum processor is incredibly difficult. That is why the industry is increasingly looking toward modular architecture. Imagine not one giant supercomputer, but a network of many quantum processors connected by optical lines. This experiment is direct proof of the viability of such an approach.
The researchers demonstrated that individual atomic memory devices can be combined into a common quantum state via photonic connections while maintaining high operational accuracy. The fidelity of the resulting entangled state was an impressive 84–88%. Furthermore, for the first time for a fully distributed multi-component quantum state, the so-called "detection loophole" was closed, and the results confirmed the violation of the Mermin inequality — a strict test for the presence of genuine quantum correlations.
A look to the future
This work continues a series of studies in the field of photonic quantum connections. Previously, the same specialists demonstrated entanglement between two remote ionic systems. Now, the architecture has been expanded to three full nodes. It is clear that the technology is still far from commercial use, but such experiments are fundamental building blocks for the future quantum internet, secure communications, and distributed computing.
My comment: This result is not just an academic achievement. It clearly demonstrates that the path to a scalable quantum computer lies not in scaling up a single chip, but in creating a quantum network. IonQ and their partners are showing that a "quantum internet" of individual atomic nodes is not science fiction, but a matter of engineering refinement. The next logical step is to increase the number of nodes and improve the accuracy of operations, which will open the door to practical applications.