For most of us, quantum physics seems like something that belongs to the invisible world of atoms and photons. It is the science of very small things, where molecules can be in two places at once, or mysteriously connected across space. But scaling up these phenomena raises a practical question: Can they become too large (more or less) to be held in your hand and still exhibit a measurable quantum effect?
At TU Wien, researchers have shown that the answer is yes. Focusing on a tiny, centimeter-sized crystal of an exotic mineral, they saw clearly Signs of quantum entanglement Not just across single atoms, but across entire scales that an amorphous solid can describe.
In a paper published in Nature Physics, the authors present a concrete connection between common properties of materials and the fundamental quantum mechanics that underpins them.
Since the beginning of quantum theory, there has been debate about whether or not quantum effects occur in large objects. Schrödinger’s cat’s original thought experiment was formulated to highlight the apparent absurdity of applying quantum rules to objects of large size.
But the TU Wien team took a different approach. “We are not trying to bring the crystal as a whole into a superposition of two states.” says Professor Silke Bühler-Baschen from the Institute of Solid State Physics at TU Wien.
“Instead, we wonder whether her voters, collectively, are in such a state of entanglement.”
Instead of Schrödinger’s cat, she compares the phenomenon to an anthill: disturb one ant, and its colony will react as a single unit. Likewise, the entangled particles in a crystal are not merely dispersed as isolated entities; Their response is regulated by their quantum correlated states, a phenomenon that cannot be explained by classical physics.
To achieve this, Quantum Fisher Information (QFI), a concept in… Quantum information theoryit was used. Physicist Peter Zoller and his group in Innsbruck originally introduced qualified foreign investors. They now provide a mathematical method for detecting entanglement in large many-body systems.
“Fisher quantum information determines how sensitive a quantum system is to change.” Böhler Passen explains. “For a collection of independent particles, the response is limited because each particle contributes on its own. However, if the particles are entangled, the entire system can respond more strongly than the sum of its individual parts.”
“It is precisely this enhanced sensitivity that makes entanglement such a valuable source of quantification, where one aims to detect very small signals with the highest possible resolution. By measuring how strongly a system responds to perturbation, one can thus infer the degree of entanglement present in the material.”
The TU Wien team then fabricated a crystal of cerium, palladium and silicon, a well-studied exotic metal known to exhibit unusual quantum properties. PhD at the Longevin Institute (ILL) in Grenoble, while setting up their experiment, PhD student Federico Mazza bombarded the crystal with neutrons to analyze how it was scattered.
“In ordinary matter, one would expect a neutron to transfer its energy to an individual particle.” Mazza explains. “But by analyzing the data using Fisher quantum information, we found a response that cannot be explained in terms of independent particles. Instead, it suggests that groups of at least nine quantum entangled entities act collectively.”
In this regard, it provides direct evidence of multipartite entanglement in a macroscopic solid (an easily visible crystal).
The motivation for this study was to better understand the strange behavior of exotic metals, a class of materials that also includes high-temperature superconductors. A collaboration between TU Wien and Rice University in 2025 showed that electrical charges flowing through these materials can be unpredictably quiet and low-noise.
A possible explanation is that this was a result of their charge carriers not disappearing but interacting (or rather coordinating) as a thermal reducer in response to temperature fluctuations.
“What we see here are not the details of a particular substance, but a general physical principle.” says Fakher Asaad of the University of Würzburg, the work’s main theorist. “The strong entanglement appears to be directly related to the unusual behavior of the exotic metals.”
“The results represent a great success for us.” He says Buhler Passion. “They confirm that our unusual approach of using methods from quantum information science to studies the solid-state physics of new materials can reveal a fundamentally new insight.”
The team’s next goal is to see if exotic metals might one day find applications in quantum technologies. “We want the transfer of knowledge between the two fields to also work in the other direction. Our goal is to explore whether exotic metals might one day find applications in quantum technologies, for example, in high-precision measurements of quantum measurement.”
But far from laboratory curiosity. This shows that quantum entanglement is not just limited to a microscopic system, but can be measured in a microscopic sample that you can hold. The strange metal appears to work in a similar way to that which allows billions of ants living together inside the same anthill to act collectively, with trillions of molecules synchronizing their actions.
This discovery shows that we can observe quantum mechanics not only in small particles but also in larger objects. It suggests that the boundaries between the quantum world and our everyday world are thinner than we thought. For everyone else, it serves as a reminder that even an ordinary-looking crystal can hide incredible secrets within, like quiet quantum whispers that echo across the universe.
Magazine reference:
- Federico Mazza et al., Quantum Fisher Information in an Exotic Metal, Nature Physics (2026). Digital ID: 10.1038/s41567-026-03298-0
