Scientists have unveiled a groundbreaking quantum state of matter that bridges two pivotal areas of physics, promising potential advancements in computing, sensing, and materials science. This discovery, detailed in a study published in Nature Physics on January 14, was co-led by Qimiao Si of Rice University. The research unites quantum criticality—where electrons oscillate between different phases—and electronic topology, which describes a quantum organization based on electron wave behaviors. The findings suggest that strong electron interactions can produce topological behavior, opening the door to new technologies utilizing this quantum state in practical applications.
“This is a fundamental step forward,” stated Si, the Harry C. and Olga K. Wiess Professor of Physics and Astronomy and director of Rice’s Extreme Quantum Materials Alliance. “Our work shows that powerful quantum effects can combine to create something entirely new, which may help shape the future of quantum science.”
Connecting Criticality and Topology
The research team developed a theoretical model to predict electron behavior under the influence of both strong interactions and topological effects. Quantum criticality typically involves electrons fluctuating between different ordered states, akin to water nearing its freezing or boiling point. Meanwhile, topology deals with the stable “twists” in the electron wave nature, which remain even as the material’s structure changes.
Traditionally, these quantum phenomena were studied in isolation. Topology was noted in materials with weak electron interactions, while quantum criticality prevailed in systems with strongly correlated electrons. The researchers aimed to challenge this longstanding separation.
“By merging these fields, we ventured into uncharted territory,” remarked Lei Chen, co-first author of the study and a graduate student at Rice. “We were surprised to find that the quantum criticality itself could generate topological behavior, especially in a setting with strong interactions.”
The study extended beyond theoretical predictions. Experimental researchers at the Vienna University of Technology, led by Silke Paschen, co-leader of the study, observed behavior in a heavy fermion material that aligned with the theoretical forecasts. This material, consisting of electrons behaving as though they are much heavier due to interactions, exhibited signs of the new topological quantum state.
Implications for Quantum Technologies
The intersection of quantum criticality and topology could revolutionize quantum technology by creating devices that are both resilient and highly sensitive—qualities essential for computing, sensing, and low-power electronics.
Topological materials are known for their resistance to disruption, while quantum criticality enhances entanglement, making this hybrid state particularly valuable for managing quantum behavior. Both effects are linked to phenomena such as superconductivity and extreme sensitivity to external signals.
“The findings address a gap in condensed matter physics by demonstrating that strong electron interactions can give rise to topological states rather than destroy them,” Si explained. “Additionally, they reveal a new quantum state with substantial practical significance.”
Charting a New Course in Materials Science
This discovery provides a roadmap for identifying or designing new materials that incorporate these quantum properties. The research team’s approach suggests seeking materials at a quantum critical point that also have potential for topological structures.
As researchers delve deeper into this new state of matter, they hope to uncover even more unusual quantum behaviors. The ability to combine quantum criticality and topology could transform how scientists approach quantum design and applications.
“Knowing what to search for allows us to explore this phenomenon more systematically,” Si noted. “It’s not just a theoretical insight; it’s a step toward developing real technologies that harness the deepest principles of quantum physics.”
The study’s co-authors include H. Hu of Rice; D.M. Kirschbaum, D.A. Zocco, F. Mazza, M. Karlich, M. Lužnik, D.H. Nguyen, A. Prokofiev, X. Yan, and J. Larrea Jimenez of the Vienna University of Technology; A. M. Strydom of the University of Johannesburg; and D. Adroja of the Rutherford Appleton Laboratory. The research received support from the Air Force Office of Scientific Research, the National Science Foundation, the Robert A. Welch Foundation, and the Vannevar Bush Faculty Fellowship.
