A three-node quantum network on atomic qubits: full distributed entanglement achieved for the first time
A team of researchers from Duke University and IonQ has achieved a breakthrough in quantum communications, demonstrating for the first time a fully distributed three-node quantum network based on individual atomic qubits. The key achievement was the formation of a three-party entangled state (GHZ state) between three remote quantum nodes connected by photonic channels.
The Essence of the Experiment
Quantum entanglement is a phenomenon where a change in the state of one particle instantly affects the state of another, regardless of distance. Previously, scientists demonstrated entanglement between two remote nodes, as well as three-node networks on other physical platforms. However, this is the first time such a result has been obtained for individual atomic qubits that can be independently controlled, read out, and scaled to build computing systems.
Why This Is a Breakthrough
The main problem with quantum computers is scaling. Building a single giant quantum processor is extremely difficult due to errors and hardware limitations. An alternative is a modular architecture: instead of a monolithic device, a network of many quantum nodes connected by photons is created. This approach resembles the development of the classical internet, where computing resources are distributed among servers.
The new experiment is a concrete step in this direction. The researchers showed that individual atomic memories can form a shared quantum state through photonic connections while maintaining high operational fidelity. During the experiment, the fidelity of the entangled state was 84–88%. Additionally, for the first time, they managed to close the "detection loophole" for a fully distributed multi-component quantum state and confirm the violation of the Mermin inequality—a test proving the presence of genuine quantum correlations.
The Path to a Quantum Internet
This work continues a series of IonQ studies 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 considered critically important building blocks for future distributed quantum computers, secure communication networks, and the quantum internet.
Expert Opinion: This achievement marks a transition from theoretical models to the practical implementation of distributed quantum systems. The ability to scale the network by adding nodes without losing entanglement quality opens the way to creating a quantum internet where computing power is distributed globally. However, commercialization will require at least another 5–7 years of intensive research, especially in improving the stability of photonic channels and reducing error rates.