Hand-sized crystal shows strong quantum entanglement
TU Wien researchers report evidence that particles in a centimeter-scale strange metal act collectively through quantum entanglement.
By Tom Brennan · Health & Medicine Correspondent
3 min read
Researchers at TU Wien say they have detected strong quantum entanglement inside a crystal large enough to hold in one hand. The finding, published in Nature Physics, suggests that a macroscopic solid can show quantum behavior usually associated with atoms, molecules and photons.
The team studied a centimeter-sized crystal made of cerium, palladium and silicon, a compound classified as a strange metal. TU Wien said the work links tools from quantum information science with solid-state physics and may help explain why strange metals behave differently from conventional materials.
A larger test of quantum behavior
Quantum effects are often examined in tiny systems that are isolated from outside interference. Silke Bühler-Paschen of TU Wien’s Institute of Solid State Physics said the group did not try to place the entire crystal into two states at once, the kind of idea made famous by Erwin Schrödinger’s cat thought experiment.
Instead, according to TU Wien, the researchers asked whether the particles inside the material were connected through collective entanglement. Bühler-Paschen compared the idea to an anthill, where a disturbance can trigger a coordinated response from many ants rather than a separate reaction from one individual.
How the measurement worked
The study used quantum Fisher information, a method from quantum information science that can reveal entanglement by measuring how strongly a system responds to a change. TU Wien credited theoretical work by Innsbruck physicist Peter Zoller and colleagues with establishing that this method can be applied to complex many-particle systems.
In a system made of independent particles, each part contributes separately to the response. TU Wien said entangled particles can produce a stronger collective response, allowing researchers to infer the presence and scale of entanglement.
At the Institut Laue-Langevin in Grenoble, PhD student Federico Mazza directed neutrons at the strange-metal crystal and measured how it reacted. According to TU Wien, the data could not be explained as neutrons passing energy to isolated particles.
The analysis indicated that groups of at least nine quantum-entangled entities were acting together, Mazza said. TU Wien described the result as direct evidence of strong multipartite entanglement in a solid object of visible size.
Why strange metals are in focus
Strange metals have drawn sustained attention because their electrical and magnetic behavior does not match standard expectations for ordinary metals. TU Wien said similar behavior appears in other systems, including high-temperature superconductors.
The university said the new evidence may clarify why strange metals show unusual electrical properties. In 2025, researchers from TU Wien and Rice University reported that current in such materials carries unusually low electrical noise; the new study suggests coordinated particle behavior could help suppress fluctuations.
Fakher Assaad of the University of Würzburg, the study’s lead theorist, said the work points to a broader physical principle linking strong entanglement with the unusual behavior of strange metals. The paper lists Mazza, Sounak Biswas, Xinlin Yan, Andrey Prokofiev, Paul Steffens, Qimiao Si, Assaad and Silke Paschen as authors.
TU Wien said the researchers now want to examine whether strange metals could aid quantum technologies, including precision measurement systems designed to detect very small signals.
This story draws on original reporting from ScienceDaily.