The Quantum Hall Effect Leaves Flatland

The quantum Hall effect (QHE) is now sufficiently “standard” that it’s the basis for a unit of measure (the ohm). But more exotic offshoots of this famously 2D phenomenon have yet to be explored, such as a 4D version predicted in 2001. This hyperdimensional “topological” material is predicted to host relativistic-like particles that carry electric current along its 3D surfaces, an effect that’s difficult to isolate in a regular solid. A way to observe the 4DQHE in a cold atomic system has now been proposed by a team of theorists from the Bose-Einstein Condensate Center in Trento, Italy, the Swiss Federal Institute of Technology (ETH) in Zurich, and the Université libre de Bruxelles, Belgium.