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Public Seminar of RPg Student:
Topological phenomena of tensor monopoles in three and higher dimensions

Speaker Mr. Qingyang MO
Affiliation The University of Hong Kong
Date June 11, 2024 (Tuesday)
Time 10:30 a.m.
Venue Room 522, 5/F, Chong Yuet Ming Physics Building, The University of Hong Kong


Tensor monopole is a topological singularity in four-dimensional space, associated with tensor gauge field. Unlike odd-dimensional monopoles in the A class, tensor monopoles belong to the AIII class and preserve chiral symmetry. Here, we reveal and observe some unique topological phenomena in acoustic tensor monopole semimetals:


  1. We explore bulk-boundary correspondence in 4D tensor monopole semimetals. Then, we observe topological boundary states in synthetic acoustic tensor monopole semimetals. Remarkably, we realize surface Dirac cones in these three-band semimetals.
  2. Tensor monopole acts as a Berry dipole in the sub-3D space, which hosts a dipolar Berry-curvature field. we experimentally demonstrate unconventional oriented Landau levels, wherein by reversing the orientation of the pseudomagnetic field, the system exhibits distinct Landau spectra. Remarkably, we observe a new type of helical zero modes whose existence critically depends on the magnetic field's orientation.
  3. When breaking down chiral symmetry in tensor monopole systems, we propose a novel topological structure in 4D: Weyl rings, characterized by the first Chern numbers, and Fermi surface boundary states.