Quantum breakthrough could unlock the secret of strange metals – and the future of superconductors

Physicists at Rice University have used quantum Fisher information to discover how quantum entanglement between electrons peaks at a critical point in strange metals, offering new insights into these mysterious materials.

Cracking the Code of Strange Metals

Strange metals have frustrated scientists for decades, but a new breakthrough by researchers at Rice University offers a significant clue: At a certain quantum critical point, the electrons in these materials become more entangled than ever before.

Using Fisher-type quantum information—a tool in quantum computing—the team revealed how quantum entanglement is amplified precisely at the point where the normal laws of electricity break down. This innovative approach not only sheds new light on the strange world of these metals, but also opens up possibilities for next-generation superconductors and energy-efficient technologies.

Quantum entanglement at the center of the mystery

Unlike ordinary metals like copper or gold, which behave predictably, strange metals behave erratically. Their electrical properties cannot be explained simply by classical physics. To investigate this, the team, led by Professor Kimiao Si, used a concept called quantum Fisher information (QFI), a tool from the field of quantum metrology that helps track changes in electron interactions under extreme conditions.

The results showed that electron entanglement, a fundamental phenomenon in quantum mechanics, reaches its peak at a point known as a "quantum critical point" – the boundary between two different states of aggregation.

"Our discoveries reveal that the strange metals have a unique pattern of entanglement, offering a new lens to understand their exotic behavior," said Si. "By leveraging quantum information theory, we uncover deep quantum correlations that were previously inaccessible."

A new approach to studying strange metals

In most metals, electrons move in an orderly manner according to known laws of physics. Strange metals break these laws, exhibiting an unusual and unexplained resistance to electricity at very low temperatures. The researchers focused on a theoretical model called the Kondo lattice, which describes the interactions between magnetic moments and the electrons that surround them.

At a certain critical transition point, the interactions become so intense that quasiparticles, the basic building blocks of electrical behavior, disappear. Using QFI, the researchers identified that the origin of the disappearance of these particles is in the entanglement of the electron spins, and found that the entanglement reaches its peak precisely at this critical point.

This innovative approach applies QFI, which is commonly used in quantum information science and precision measurements, to the study of metals. "By combining quantum information science with solid-state physics, we are creating a new direction in materials research," said C.

A possible path to more efficient energy

The researchers' theoretical calculations surprisingly matched real experimental results, particularly data from inelastic neutron scattering, a method for studying materials at the atomic level. This connection strengthens the hypothesis that quantum entanglement plays a central role in the behavior of strange metals.

Understanding these strange metals is not only a scientific challenge, but could lead to significant technological benefits. These materials are close in properties to high-temperature superconductors, which have the potential to conduct electricity without energy loss. Understanding them could revolutionize power grids and make energy transmission more efficient.

The study also demonstrates how quantum information tools can be applied to the study of other exotic materials. Strange metals could play a key role in future quantum technologies, where enhanced entanglement is a valuable resource. The study provides a new framework for characterizing these complex materials by detecting the peak moment of quantum entanglement.