Researchers at the University of Innsbruck have shown that quantum sensors can remain highly accurate even in extremely noisy conditions. It's the first experimental realization of a powerful quantum sensing protocol, outperforming all comparable classical strategies-even under overwhelming noise.
Quantum sensors promise unprecedented measurement precision, but their advantage can quickly erode in realistic environments where noise dominates. Researchers led by Ben Lanyon at the Department of Experimental Physics from the University of Innsbruck have now shown how to overcome this obstacle. Their new work shows that, with the right kind of quantum preparation, sensors can stay protected from disruptive noise while still detecting the signals scientists want to measure.
Using three calcium ions held in place by electric fields, the research team created a special type of quantum entanglement that allows the sensors to ignore unwanted disturbances. Even when the team introduced rapidly changing magnetic noise-strong enough to defeat all standard sensing methods-the entangled sensors remained accurate. "Even under noise conditions that overwhelm standard methods, our entangled sensing protocol continues to operate at the theoretical optimum," says lead experimentalist James Bate. "We find that the quantum-enhanced approach not only survives the noise-it decisively outperforms any possible classical or unentangled strategy."
The results provide the first implementation of a theoretically optimal strategy for sensing spatially distributed fields using entangled quantum sensors. The method was recently proposed by a team around Wolfgang Dür from the Department of Theoretical Physics at the University of Innsbruck. It uses entangled states engineered to be simultaneously maximally sensitive to a target field and immune to noise that has a different spatial profile. "One of the most compelling aspects of this method is that it requires far fewer resources than quantum error-correcting codes but can achieve equivalent optimality for this class of sensing tasks," explains Wolfgang Dür.
Beyond the proof-of-principle demonstration with three ions, the authors show theoretically that the quantum advantage scales exponentially as the complexity of the sensed field increases. Because the protocol relies only on relative sensor positioning and the ability to generate multipartite entanglement, it is readily extendable to future quantum sensor networks using ions, atoms, solid-state spins, or other platforms.
"This experiment shows that entanglement delivers a practical and robust advantage in real-world sensing scenarios," says Ben Lanyon. "As quantum networks continue to mature, distributed quantum sensors will become a key application-one where noise resilience is not just beneficial, but essential." These findings highlight the potential for creating networks of quantum sensors capable of operating across laboratories, cities, or even continents. Such systems could one day monitor environmental changes, search for new physical phenomena, or significantly improve technologies that rely on ultra-precise measurements.
The study is the result of a collaboration within the Quantum Science Austria (QuantA) cluster of excellence and has been published in Physical Review Letters. It was financially support by the Austrian Science Fund FWF, the Austrian Research Promotion Agency FFG and the European Union, among others.
Publication: Experimental Distributed Quantum Sensing in a Noisy Environment. J. Bate, A. Hamann, M. Canteri, A. Winkler, Z. X. Koong, V. Krutyanskiy, W. Dür, and B. P. Lanyon. Phys. Rev. Lett. 2025 DOI: 10.1103/3hgx-wcdn
