Breakthrough in quantum networks: three remote atomic qubits entangled for the first time — a step toward a modular quantum computer
A research team from Duke University and IonQ has achieved a significant breakthrough in quantum communications. For the first time in history, they have successfully created a fully distributed three-node quantum network based on individual atomic qubits. The key achievement was the formation of a three-party entangled state, known as the Greenberger-Horne-Zeilinger (GHZ) state, between three remote nodes connected by photonic channels.
What This Means for Quantum Technologies
The phenomenon of quantum entanglement, where a change in the state of one particle instantly affects others regardless of distance, is a cornerstone of future quantum networks. Previously, scientists have successfully demonstrated entanglement between two nodes and built three-node networks on alternative platforms. However, the current experiment is unique in that such a result has been achieved for the first time on individual atomic qubits. These qubits have a key advantage: they can be independently controlled, read out, and, most importantly, scaled to build full-fledged computing systems.
Why This Is a Breakthrough in Scaling
The main headache for quantum computer developers is scaling. Creating a single giant quantum processor involves enormous technical difficulties due to errors and hardware limitations. This is why an increasing number of experts are betting on a modular architecture. Instead of one monolithic chip, they propose building a network of many quantum nodes connected by photons. This approach resembles the evolution of the classical internet, where resources are distributed across thousands of servers. The new experiment is a direct step in this direction.
The researchers not only demonstrated the possibility of forming a shared quantum state via photonic connections but also achieved impressive accuracy metrics. The fidelity of the resulting entangled state was 84–88%. Moreover, for the first time, the so-called "detection loophole" was closed for a fully distributed multi-component quantum state. The results also confirmed the violation of the Mermin inequality, one of the strictest tests for the presence of genuine quantum correlations.
Looking to the Future
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 successfully expanded the architecture to three full-fledged nodes. Although commercial application of the technology is still far off, such experiments are critically important building blocks for future distributed quantum computers and secure communication networks.
Analyst's Opinion: This experiment is not just a scientific curiosity but a crucial engineering signal. It proves that the approach of "many small quantum processors united in a network" is viable. For cryptography, this means that the threat from quantum computing is becoming not abstract but quite tangible, albeit on a horizon of 10-15 years. Investors and developers in the blockchain space should already be closely monitoring progress in modular quantum systems.