A quantum network with three atomic qubits: the first step towards a modular quantum internet
Engineers and physicists from Duke University, together with the IonQ team, have achieved a breakthrough in the field of distributed quantum systems. For the first time in history, they have successfully formed a three-party entangled state (GHZ state) between three remote atomic qubits connected via photonic channels. This is not just a laboratory curiosity—it is the first full-fledged demonstrator of a fully distributed three-node quantum network based on individual atoms.
The Essence of the Experiment
Quantum entanglement is a phenomenon where a change in the state of one particle instantly affects another, regardless of distance. Previously, scientists have demonstrated entanglement between two nodes and even built three-node networks on other platforms (e.g., superconducting qubits or photons). However, the key difference of this new work is the use of individual atomic qubits, which can be independently controlled, read out, and, most importantly, scaled to build computational modules.
Why This Is Critically Important
The main problem with modern quantum computers is scaling. Creating a single giant processor without errors is practically impossible. 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 photons is built. This is a direct analogy to the classical internet, where computing power is distributed across thousands of servers.
In the experiment, the scientists achieved an entangled state fidelity of 84–88%. Moreover, they closed the so-called "detection loophole" for a fully distributed multi-component quantum state for the first time and confirmed the violation of the Mermin inequality—a rigorous test for the presence of genuine quantum correlations. This means that the resulting state is not a statistical coincidence but a true quantum resource.
The Path to a Quantum Internet
This work is a logical continuation of a series of IonQ experiments in photonic quantum connections. Previously, the company demonstrated entanglement between two remote ion systems, and now it has expanded the architecture to three full 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: The breakthrough in three-node entanglement on atomic qubits is not just a scientific sensation but a practical signal to the market. IonQ and Duke are showing that the modular architecture is viable, and this directly impacts investment strategies in the quantum computing sector. The next step is to increase the number of nodes to dozens, and then we will see the first prototypes of quantum clusters capable of solving real-world problems.