Scientists have created a three-way quantum entanglement on individual atoms for the first time — a breakthrough toward the quantum internet.
A group of researchers from Duke University and IonQ has taken a significant step in the development of distributed quantum computing. In their experiment, they successfully implemented, for the first time, three-way entanglement (Greenberger–Horne–Zeilinger state) between three remote atomic qubits connected via photonic channels. This is the world's first fully distributed three-node quantum network based on individual atomic systems.
What Happened
Quantum entanglement is a phenomenon where two or more particles remain instantly connected, regardless of the distance between them. A change in the state of one particle is immediately reflected in the others. This property underpins future quantum networks and the so-called quantum internet.
Previously, scientists had demonstrated entanglement between two remote nodes, as well as three-node networks on other physical platforms (e.g., photons or superconducting circuits). However, this is the first time such a result has been achieved with individual atomic qubits—systems that can be independently controlled, read out, and, crucially, scaled to build full-fledged computing machines.
Why This Is a Breakthrough
The main challenge of modern quantum computers is scaling. Creating a single giant quantum processor with thousands of qubits is extremely difficult due to errors, noise, and hardware limitations. This is why the industry is increasingly shifting toward a modular architecture: instead of one monolithic device, a network of many quantum nodes connected by photonic communication lines is built. This approach mirrors the development of the classical internet, where computing resources are distributed across thousands of servers.
The new experiment is direct proof of the viability of this strategy. The researchers showed that individual atomic memories can form a shared quantum state through photonic connections while maintaining high fidelity of quantum operations. In the experiment, the fidelity of the entangled state reached 84–88%. Additionally, the scientists closed the so-called "detection loophole" for a fully distributed multi-component quantum state for the first time. The results also confirmed the violation of the Mermin inequality—one of the key tests proving the presence of genuine quantum correlations rather than classical statistical coincidences.
A Step Toward the Quantum Internet
This work continues a series of IonQ studies on photonic quantum connections. Previously, the company demonstrated entanglement between two remote ion systems, and now it has expanded the architecture to three full-fledged nodes. Although the technology is still far from commercial application, such experiments are fundamental building blocks for future distributed quantum computers, secure communication networks, and, ultimately, the quantum internet.
My comment: Achieving three-way entanglement on individual atoms is not just a record but a demonstration that the modular approach to quantum computing truly works. If before we spoke of the "quantum internet" as a distant futuristic concept, now we have a working prototype of its basic element. The key indicator of progress here is the closure of the "detection loophole," which rules out the possibility of a classical interpretation of the results. This means the technology is moving from the realm of laboratory curiosities into the domain of engineering-reproducible solutions. The next step is to increase the number of nodes and improve fidelity to levels suitable for error correction.