Dresden 2020 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 12: Topological Insulators 2 (joint session TT/HL)

TT 12.7: Talk

Monday, March 16, 2020, 16:30–16:45, HSZ 103

Fractional corner charges in a 2D super-lattice Bose-Hubbard model — •Julian Bibo^1,4, Izabella Lovas^1,4, Yizhi You³, Fabian Grusdt^1,2,4,5, and Frank Pollmann^1,4 — ¹Technische Universität München — ²Ludwig-Maximilians-Universität München — ³Princeton Center for Theoretical Science — ⁴Munich Center for Quantum Science and Technology — ⁵Department of Physics and Institute for Advanced Study, Technical University of Munich

Higher order topological insulators (HOTIs) represent a novel class of topological phases protected by a combination of spatial and internal symmetries. While many non-interacting system have been introduced and studied, it is unclear to which extend the results obtained in non-interacting systems transfer to their strongly-interacting counter parts. In our work, we introduce an experimentally accessible model, a 2D super-lattice Bose-Hubbard model on a square lattice at half-filling, that realizes a robust higher order topological phase protected by charge conservation and fourfold rotation symmetry. Excitingly, our model predicts the presence of symmetry protected fractional charges e/2 to occur at the corners. The presence and robustness of the predicted fractional corner charges is confirmed using the Density Renormalisation Group Ansatz (DMRG). Finally, we propose a way to measure the characteristic fractional corner charges and also provide simulations for the measurement.