Strange metals have long puzzled scientists with their unusual electrical and magnetic properties, but now a team of Rice University physicists has developed a quantum information tool for probing those peculiar behaviors.
The materials don’t conform to the standard rules of magnetism and electricity at very low temperatures, which the Rice team discovered is due to their electrons becoming entangled at a quantum tipping point. With the current supply chain focus on semiconductors to power quantum computing and AI, the discovery holds immense potential for future energy-use applications.
Strange Metals Explained
Conventionally, manufacturers use well-understood metals like copper or gold to conduct energy in circuits and microchips. However, the previously unpredictable and complex behaviors associated with some metals have made them impractical for such applications.
These “strange metals” are essentially composed of materials that show unusual electrical behavior, such as resistance increasing proportionally to temperature. Such characteristics defy the expected behavior of ordinary metals.
The Rice team, led by Qimiao Si, sought to illuminate the behaviors of these metals by applying a quantum metrology concept called quantum Fisher information (QFI) to the problem. QFI allows researchers to measure electron interactions under extreme conditions.
Their work found a quantum tipping point driving the strange metals’ unusual qualities—the defiance of conventional rules of electricity and magnetism peaks at the transition between two 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.”
Cracking Strange Behavior
The Rice University team employed the Anderson/Kondo lattice theoretical model near its Kondo destruction quantum critical point to understand how magnetic moments and surrounding electrons interact. They found that during a critical tipping point, fundamental building blocks of electrical behavior called quasiparticles disappear under the intense interactions.
Using QFI, Si’s team discovered the quasiparticle loss originating from electron spin entanglements. Their work is a novel application of a technique used mainly in quantum information research.
“By integrating quantum information science with condensed matter physics, we are pivoting in a new direction in materials research,” Si said.
Si’s team’s findings showcase an example of quantum entanglement, where the quantum state of one particle is directly connected to that of another. Given the collectivized nature of strange metal particles, quantum information techniques are the best way to understand complex behaviors.
New Energy Efficiency
Real-world experimental results probing materials at the atomic level with inelastic neutron scattering buoyed the Rice team’s theoretical work. Connecting their QFI research to practical results strengthens the case for how quantum entanglement is at the heart of strange metals’ unusual behavior. Further work to unravel strange metals has major implications for energy efficiency.
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High-temperature superconductors currently used in energy storage and transmission are similar to strange metals. Si’s teams believe that with further work, the strange metals could be used in lossless energy transmission, improving the efficiency of power grids. The complex entanglement properties displayed by strange metals could also be a boon in quantum technologies of the coming years.
Beyond the team’s immediate focus, their application of QFI demonstrates the concept’s utility for exploring other exotic materials.
The paper “Amplified Multipartite Entanglement Witnessed in a Quantum Critical Metal” appeared on March 14, 2025, in Nature Communications.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted atryan@thedebrief.org, and follow him on Twitter@mdntwvlf.