Topolectrical-circuit realization of a four-dimensional hexadecapole insulator

It is very attractive to explore topological physics beyond three-dimensional space. This work experimentally demonstrates the realization of a classical analog of higher order/dimensional topological phases in electric circuits. Multiple robust corner states have been observed. These result from the nontrivial hexadecapole moment and may have potential applications in the field of topological analog signal processing with multiple channels. The authors expect that experimental access to higher order/dimensional topological physics with electric circuits can provide a valuable reference for investigating the higher-dimensional topological phase in full real space.