Strange metals have baffled scientists for decades, but a new breakthrough from Rice University researchers offers a major clue: at a specific quantum tipping point, electrons in these materials become more entangled than ever before.
Using quantum Fisher information, a tool from the world of quantum computing, the team revealed how entanglement spikes right as the usual rules of electrical behavior break down. This fresh approach not only sheds light on the weird world of strange metals but also opens doors to next-generation superconductors and energy-efficient technologies.
Cracking the Code of Strange Metals
Scientists have long been puzzled by strange metals, materials that don’t follow the usual rules of electricity and magnetism. Now, physicists at Rice University have made a major breakthrough using a tool from quantum information science.
In a new study published in Nature Communications, they show that electrons in strange metals become highly entangled at a key tipping point. This finding offers fresh insight into the behavior of these unusual materials and could eventually lead to improvements in superconductors – technologies that may one day revolutionize how we transmit and use energy.
Quantum Entanglement at the Heart
Unlike everyday metals like copper or gold, which behave in predictable ways, strange metals act far more erratically. Their electrical properties can’t be easily explained using standard physics. To investigate, the team – led by Qimiao Si, a professor of physics and astronomy at Rice – used a concept called quantum Fisher information (QFI). This tool, borrowed from quantum metrology, helps scientists track how electron interactions change under extreme conditions.
Their results show that electron entanglement, a fundamental feature of quantum mechanics, reaches its peak at what’s known as a quantum critical point, the boundary between two different states of matter.
“Our findings reveal that strange metals exhibit a unique entanglement pattern, which offers a new lens to understand their exotic behavior,” Si said. “By leveraging quantum information theory, we are uncovering deep quantum correlations that were previously inaccessible.”
A New Way to Study Strange Metals
In most metals, electrons move in an orderly fashion, following well-established laws of physics. Strange metals, however, break these rules, showing unusual resistance to electricity and behaving in unusual ways at very low temperatures. To explore this puzzle, the researchers focused on a theoretical model called the Kondo lattice, which describes how magnetic moments interact with surrounding electrons.
At a critical transition point, these interactions become so intense that the fundamental building blocks of electrical behavior, known as quasiparticles, vanish. Using QFI, the researchers tracked the origin of this quasiparticle loss to how electron spins become entangled, finding that entanglement reaches its peak precisely at this quantum critical point.
Bridging Quantum and Materials Science
This novel approach applies QFI, primarily used in quantum information and precision measurements, to the study of metals.
“By integrating quantum information science with condensed matter physics, we are pivoting in a new direction in materials research,” Si said.
Possible Path to More Efficient Energy
The researchers’ theoretical calculations unexpectedly matched real-world experimental data, specifically aligning with results from inelastic neutron scattering, a technique used to probe materials at the atomic level. This connection reinforces the idea that quantum entanglement plays a fundamental role in the behavior of strange metals.
Understanding strange metals is more than just an academic challenge; it could have significant technological benefits. These materials share a close connection with high-temperature superconductors, which have the potential to transmit electricity without energy loss. Unlocking their properties could revolutionize power grids, making energy transmission more efficient.
The study also demonstrates how quantum information tools can be applied to other exotic materials. Strange metals could play a role in future quantum technologies, where enhanced entanglement is a valuable resource. The research provides a new framework for characterizing these complex materials by showing when entanglement peaks.
Reference: “Amplified multipartite entanglement witnessed in a quantum critical metal” by Yuan Fang, Mounica Mahankali, Yiming Wang, Lei Chen, Haoyu Hu, Silke Paschen and Qimiao Si, 14 March 2025, Nature Communications.
DOI: 10.1038/s41467-025-57778-7
The research team included Rice’s Yuan Fang, Yiming Wang, Mounica Mahankali and Lei Chen along with Haoyu Hu of the Donostia International Physics Center and Silke Paschen of the Vienna University of Technology. Their work was supported by the National Science Foundation, the Air Force Office of Scientific Research, the Robert A. Welch Foundation and the Vannevar Bush Faculty Fellowship program.
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