Quantum physics shows that particles do not behave like solid objects with fixed positions. Instead, they also act like waves, which means their exact location in space cannot be pinned down. Even so, in many practical situations, scientists can still rely on a familiar, classical description. They often picture particles as tiny objects moving through space at a certain speed.
This simplified view is especially useful when explaining how electricity moves through metals. Physicists typically describe electric current as electrons rushing through a material, where they are pushed, slowed, or redirected by electromagnetic forces.
Many modern theories also build on this particle-based description. One prominent example is the idea of topological states of matter, a breakthrough that earned the Nobel Prize in Physics in 2016. These theories assume that electrons behave like particles with clear energies and velocities.
However, researchers have identified materials in which this picture no longer applies (see publication below). In these cases, electrons cannot be described as small objects with a precise position or a single, well-defined speed.
Now, a team at TU Wien has shown that even when electrons lose this particle-like behavior, the material can still exhibit topological properties. Until now, such properties had always been explained using particle-based models. The new results show that topology applies more broadly than expected, bringing together ideas that once seemed incompatible.
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