Writing in Physical Review Letters, Prof. Chih-Chun Chien and colleagues show how principles of topological protection and symmetry apply to a classical, and not just quantum, systems. Using electric circuits with elements that exhibit memory effects, a phenomenon known as custodial symmetry originally proposed in particle physics manifests itself by protection of an exotic state associated with a symmetry that is broken by the memory elements. Thanks to the commercial availability of electric elements with memory effects, this work offers another example of demonstrating universal physics concepts in tabletop experiments.
