Breakthrough in quantum networks: entanglement of three remote atomic qubits created for the first time
The world of quantum technologies is taking another decisive step forward. A team of researchers from Duke University, together with engineers from IonQ, has announced the creation of the first fully distributed three-node quantum network based on individual atomic qubits. This event marks a crucial milestone on the path to a practical quantum internet.
The key achievement was the formation of a so-called three-party entangled state, known as the Greenberger-Horne-Zeilinger (GHZ) state, between three remote quantum nodes. These nodes were interconnected via photonic channels, enabling the creation of a unified quantum system where a change in the state of one particle instantly affects the others, regardless of distance.
Why is this a turning point?
Until now, successful experiments in quantum entanglement have generally been limited to two nodes. Although three-node networks have been demonstrated on other physical platforms, working with individual atomic qubits is of particular interest. Atomic qubits offer high stability and are potentially suitable for scaling into full-fledged computing systems, where each node can be independently controlled and read out.
The main challenge in modern quantum engineering is scaling. Creating a single large quantum processor without critical errors is practically impossible. The alternative approach, which the scientists demonstrated, is a modular architecture. Instead of a monolithic computer, a network of many quantum nodes connected by photons is built. This resembles the development of the classical internet, where computing power is distributed among servers.
Technical details and significance
In the experiment, the researchers achieved an entangled state fidelity of 84–88%. Moreover, for the first time, they managed to close the so-called "detection loophole" for a fully distributed multi-component quantum state. This means the results cannot be explained by classical effects or measurement errors. Additional confirmation came from the violation of the Mermin inequality, one of the strictest tests for the presence of genuine quantum correlations.
The work continues a series of IonQ studies in the field of photonic quantum connections. Previously, the company demonstrated entanglement between two remote ion systems, and now it has successfully expanded the architecture to three full-fledged nodes. Although commercial application is still far off, it is precisely such experiments that lay the foundation for future distributed quantum computers, secure communication networks, and ultimately, the quantum internet.
Expert commentary: This experiment is not just a technical curiosity. It proves that the modular architecture of quantum networks based on atomic qubits is viable. Closing the "detection loophole" is a particularly important step, as it eliminates the last doubts about the true quantum nature of the observed correlation. We are witnessing how the outline of a future global quantum infrastructure is gradually emerging from disparate laboratory demonstrations.