2020/05/31 by F. Nur Ünal, Adrien Bouhon, Robert-Jan Slager · 2 citations
Physics and Astronomy · #cond-mat.quant-gas #cond-mat.mes-hall #physics.atom-ph #quant-ph
paper · pdf · doi:10.1103/physrevlett.125.053601
published as Phys. Rev. Lett. 125, 053601 (2020) · 6+7 pages, 3+3 figures; new version features improved exposition and new appendix describing simplified models
arxiv created 2020/07/27 · arxiv updated 2020/07/28
The last years have witnessed rapid progress in the topological characterization of out-of-equilibrium systems. We report on robust signatures of a new type of topology -- the Euler class -- in such a dynamical setting. The enigmatic invariant (ξ) falls outside conventional symmetry-eigenvalue indicated phases and, in simplest incarnation, is described by triples of bands that comprise a gapless pair, featuring 2ξ stable band nodes, and a gapped band. These nodes host non-Abelian charges and can be further undone by converting their charge upon intricate braiding mechanisms, revealing that Euler class is a fragile topology. We theoretically demonstrate that quenching with non-trivial Euler Hamiltonian results in stable monopole-antimonopole pairs, which in turn induce a linking of momentum-time trajectories under the first Hopf map, making the invariant experimentally observable. Detailing explicit tomography protocols in a variety of cold-atom setups, our results provide a basis for exploring new topologies and their interplay with crystalline symmetries in optical lattices beyond paradigmatic Chern insulators.