Breakthrough in Quantum Networks: Three-Way Entanglement Created for the First Time on Distant Atomic Qubits
Quantum entanglement is a phenomenon where a change in the state of one particle instantly affects another, regardless of distance. Until now, this effect has been demonstrated mainly in laboratory conditions on two nodes. However, researchers from Duke University and IonQ have recently made a significant step forward: they have, for the first time, created three-way entanglement between individual atomic qubits distributed across three remote nodes. This achievement, known as the Greenberger-Horne-Zeilinger (GHZ) state, opens new horizons for modular quantum computing architectures.
What was done?
In the experiment, the researchers connected three quantum nodes using photonic channels — light pulses that transmit quantum information. A key feature was the use of individual atomic qubits that can be independently controlled, read, and, most importantly, scaled. Previously, similar results were achieved only on other platforms, such as superconducting circuits, but not on atomic systems, which are considered more promising for long-term information storage.
The scientists achieved a fidelity of the entangled state of 84–88% and, for the first time, closed the so-called "detection loophole" — a vulnerability that could cast doubt on the authenticity of quantum correlations. Additionally, the results confirmed the violation of Mermin's inequality, serving as rigorous proof of the presence of true quantum entanglement.
Why is this a breakthrough?
The main problem with modern quantum computers is scaling. Building one large processor with thousands of qubits is extremely difficult due to error accumulation and physical limitations. An alternative approach is a modular architecture, where instead of one giant chip, a network of many quantum nodes connected by photons is created. This resembles the development of the classical internet: computing resources are distributed but work as a single whole.
The new experiment is the first practical step toward such a distributed system based on atomic qubits. It proves that individual atomic memories can form a common quantum state through photonic connections while maintaining high operational accuracy. This is critically important for future quantum networks, secure communications, and, ultimately, the quantum internet.
My expert opinion
This achievement is not just a laboratory curiosity. It demonstrates that the modular approach to quantum computing is viable on an atomic platform. However, commercial application should not be expected in the coming years. The technology is still at the fundamental research stage, and transitioning from three nodes to hundreds will require years of work on the stability of photonic channels and error reduction. Nevertheless, it is steps like these that turn the quantum internet from science fiction into an engineering challenge.