Quantum entanglement in a hand-sized crystal

Researchers from the Vienna University of Technology have observed quantum entanglement in a crystal large enough to be held in the hand. The crystal is made of cerium, palladium, and silicon and is classified as a strange metal, known for its unusual electrical behavior that defies traditional explanations.

Entanglement among multiple quantum entities

The team did not attempt to put the entire crystal in two states at once but instead investigated whether particles within the material shared a common quantum state. Quantum entanglement means that particles are no longer independent, and their states are correlated. In this crystal, groups of at least nine quantum entities reacted together in a coordinated manner.

Experiments under extreme conditions

To observe this phenomenon, the researchers used neutrons at the Laue-Langevin Institute in Grenoble, at a temperature as low as 60 millikelvins and under a precisely controlled magnetic field. They measured how the crystal responded to the neutrons' impact using a technique known as quantum Fisher information, which assesses how sensitive a quantum system is to small changes.

Surprising size of the entangled material

The discovery is notable because quantum entanglement is typically studied in atoms, photons, and microscopic objects that need careful isolation. Here, the entangled material is visible to the naked eye, measuring about one centimeter in size and easily held in a hand. Inside, multiple quantum entities are strongly entangled.

Implications for strange metals and superconductors

The researchers suggest that the observed entanglement could explain some of the unusual properties of strange metals. Similar behaviors are seen in high-temperature superconductors, where electric current flows with minimal resistance. This study may provide a new perspective on how these materials function at the quantum level.

Potential applications in quantum technologies

The findings could influence the development of quantum technologies, as strongly entangled materials are highly sensitive to disturbances. This sensitivity could be used to design sensors capable of detecting extremely weak signals. The study shows that quantum physics is not confined to the microscopic world, as even a hand-held crystal exhibits signs of quantum entanglement.