Physicists have uncovered a subtle magnetic order within the pseudogap phase of quantum materials, potentially explaining the path to superconductivity. Using an ultracold quantum simulator, researchers observed persistent magnetic patterns that align with the pseudogap's formation temperature. This finding could advance the development of high-temperature superconductors for energy-efficient technologies.
Superconductivity, the phenomenon where materials conduct electricity without resistance, holds promise for revolutionizing power transmission and quantum computing. Yet, in high-temperature superconductors, the transition to this state often involves a mysterious intermediate phase called the pseudogap, where electrons exhibit unusual behavior and reduced conductivity.
A new study challenges long-held views on this pseudogap. Researchers found that even after doping—removing electrons to alter the material—disrupts apparent magnetic order, a hidden, universal magnetic pattern endures at extremely low temperatures. This pattern closely mirrors the temperature at which the pseudogap emerges, suggesting magnetism plays a crucial role in setting the stage for superconductivity.
The discovery stems from experiments simulating the Fermi-Hubbard model with lithium atoms cooled to billionths of a degree above absolute zero in an optical lattice formed by lasers. Using a quantum gas microscope, the team captured over 35,000 images of individual atoms, revealing correlations among up to five particles—far beyond typical pair-focused studies.
"Magnetic correlations follow a single universal pattern when plotted against a specific temperature scale," said lead author Thomas Chalopin of the Max Planck Institute of Quantum Optics. "And this scale is comparable to the pseudogap temperature, the point at which the pseudogap emerges."
The work builds on theoretical predictions from a 2024 Science paper and involved collaboration between experimentalists at the Max Planck Institute in Germany and theorists at the Center for Computational Quantum Physics in New York, led by Antoine Georges.
"It is remarkable that quantum analog simulators based on ultracold atoms can now be cooled down to temperatures where intricate quantum collective phenomena show up," Georges noted. The findings, published in the Proceedings of the National Academy of Sciences in 2026, provide a benchmark for pseudogap models and highlight the value of theory-experiment partnerships in probing quantum matter.
