Scientists discover 'impossible' quantum state at near absolute zero

Scientists at Vienna University of Technology (TU Wien), collaborating with theorists from Rice University, have discovered a novel quantum state that defies traditional physics assumptions about electron behavior at ultra-low temperatures near absolute zero. Using a cerium-ruthenium-tin (CeRu₄Sn₆) material cooled to below one degree above absolute zero, they observed a spontaneous anomalous Hall effect without any external magnetic field—a hallmark of topological behavior. This finding challenges the long-held belief that topological states require electrons to behave as well-defined particles with clear velocities and energies. Instead, the material exhibited intense quantum fluctuations where the usual quasiparticle model breaks down, yet topological properties still emerged. The research reveals that topological states can exist in a more abstract mathematical form, independent of particle-like electron states, leading to the identification of a new quantum phase termed an "emergent topological semimetal." This discovery broadens the understanding of topology in quantum materials and suggests that quantum critical