A crystal small enough to fit in the palm of your hand contains one of the most remarkable quantum phenomena ever recorded in a macroscopic object. Researchers at TU Wien have experimentally confirmed the existence of strong multipartite quantum entanglement for the first time—a state where particles cease to be independent units and begin to behave as a coordinated whole.
The team is led by Professor Silke Bühler-Pashen from the Institute of Solid State Physics at TU Wien. Her group investigated a crystal composed of cerium, palladium, and silicon (Ce3Pd20Si6)—a so-called "strange metal" that has long been known to physicists but remains a mystery. These materials exhibit unusual electrical and magnetic properties that classical physics is simply unable to explain.
The experimental work was conducted at the Institut Laue-Langevin (ILL) in Grenoble, France—one of the world's premier centers for neutron science. PhD student Federico Mazza bombarded the crystal with a neutron beam and measured its response to the disturbance. Inelastic neutron scattering allowed the researchers to obtain a detailed picture of the material's internal structure at extremely low temperatures within a precisely tuned magnetic field.
To analyze the results, the scientists employed a tool from quantum information science known as Quantum Fisher Information (QFI), a method developed by Innsbruck theorist Peter Zoller and his group. The concept is straightforward: if quantum entanglement is present in a system, it will react to external perturbations significantly more strongly than the combined independent reactions of individual particles. By measuring the system's sensitivity, one can determine the degree of entanglement hidden within the material.
In an ordinary crystal, a neutron passing through would transfer its energy to a single individual particle. Something entirely different happened here: the data revealed a collective response that cannot be explained by the simple sum of independent contributions. Calculations showed that groups of at least nine quantum particles are involved in the entangled state, acting as a single entity.
A vivid analogy helps illustrate what is occurring here. Imagine an anthill: when it is disturbed, it is not just each ant running around chaotically that reacts, but the entire colony responding as a single organism. In the same way, the particles in the crystal exhibit collective behavior—they are quantum-mechanically interconnected and organized at a profound level.
The results, published in the journal Nature Physics in June 2026, carry fundamental significance. They confirm that strong multipartite quantum entanglement is not a rarity in strange metals but rather an inherent property. This entanglement appears to explain their unusual characteristics: the linear change in electrical resistance with temperature at low values—behavior that defies standard electronic theory of metals—and particularly low levels of electrical noise, a phenomenon that has long baffled experimentalists.
The discovery creates an unexpected bridge between two fields of physics: quantum information science and condensed matter physics. It demonstrates that quantum metrology methods, developed in laboratories using single atoms and photons, can be applied directly to macroscopic samples of real materials without requiring perfect isolation from the surrounding environment. This means the boundary between the "classical" and "quantum" worlds is not located where textbooks have traditionally drawn it.
The prospects are both vast and practical. Materials with this level of quantum entanglement could form the basis for creating ultra-sensitive quantum sensors—devices capable of detecting signals so weak they are inaccessible to classical detectors. This could revolutionize measurement technologies in medical diagnostics, geophysics, and fundamental physics.
