The first experimental realisation of Floquet tensor monopoles provides a controllable platform for investigating non-equilibrium topology in four dimensions

Artistic impression of a topological metal (Credit: iStock/Lee-Yiu-Tung)

Ever since Paul Dirac proposed the magnetic monopole in 1931, physicists have searched for particles carrying a single magnetic pole, so far without success. But monopole-like objects can also emerge as unusual points in the energy landscapes of materials and artificial systems.

These objects help reveal how topology, the mathematics of properties that survive continuous deformation, shapes physical behaviour. Recent experiments have pushed this idea beyond familiar three-dimensional settings by creating tensor monopoles .

Tensor monopoles are singular points in a four-dimensional band structure.…