Physicists have uncovered a new quantum phenomenon, proving for the first time that electrons can form vortex-like structures in momentum space. This breakthrough, led by researchers at the Universities of Würzburg and Dresden, sheds light on how electrons behave in topological semimetals and may pave the way for energy-efficient quantum technologies. Mapping Quantum Tornadoes in Momentum Space Understanding how electrons move in materials is central to modern physics. Traditional research focuses on position space, where familiar vortex structures appear in fluids, superfluids, and superconductors. Sketch of the TaAs Brillouin zone with a symmetry-enforced almost movable WNL, denoted in green. (CREDIT: Physical Review X) However, momentum space—which describes electron behavior in terms of energy and movement direction—has remained largely unexplored for such phenomena. Scientists have long theorized that electrons could form vortex-like patterns in momentum space, but until now, experimental confirmation was missing. Using soft x-ray angle-resolved photoelectron spectroscopy (SX-ARPES), researchers mapped the three-dimensional momentum space of tantalum arsenide (TaAs), a quantum semimetal known for hosting exotic electronic states. Their findings, published in the journal Physical …