1. School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China 2. School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China 3. International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China 4. Collaborative Innovation Center of Quantum Matter, Beijing 100871, China 5. CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
We discover a new wave localization mechanism in a periodic wave system, which can produce a novel type of flat band and is distinct from the known localization mechanisms, i.e., Anderson localization and flat band lattices. The first example we give is a designed electron waveguide (EWG) on 2DEG with special periodic confinement potential. Numerical calculations show that, with proper confinement geometry, electrons can be completely localized in an open waveguide. We interpret this flat band localization (FBL) phenomenon by introducing the concept of self-localized orbitals. Essentially, each unit cell of the waveguide is equivalent to an artificial atom, where the self-localized orbital is a special eigenstate with unique spatial distribution. These self-localized orbitals form the flat bands in the waveguide. Such self-localized orbital induced FBL is a general phenomenon of wave motion, which can arise in any wave systems with carefully engineered boundary conditions. We then design a metallic waveguide (MWG) array to illustrate that similar FBL can be readily realized and observed with electromagnetic waves.
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See Supplemental Material I for the calculations about the EWGs.
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See Supplemental Material II for the Fermi level in EWG.
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See Supplemental Material III for the wave functions in the bump.
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See Supplemental Material IV for other artificial orbitals in EWG.
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See Supplemental Material VII for this self-localized orbits.
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