Fig. 6: Experimental concept and physical parameters for realizing spherical flat bands.
From: Flat bands on a spherical surface from Landau levels to giant-quantum-number orbitals
a The figure schematically illustrates the flat band on the spherical surface with the strength of the magnetic monopole Q = 0 and a zero-field system designed to host a Bell pair, where the blue solid rectangles represent orbitals occupied by electrons, the purple hollow rectangles indicate unoccupied orbitals, and the region enclosed by red dotted lines corresponds to the partially filled flat band with orbital angular momentum l. The inner sphere represents the spherical substrate, while the outer shell represents a layer of two-dimensional electron gas (2DEG), such as that in indium antimonide (InSb) and gallium arsenide (GaAs). The gray cone indicates the scanning tunneling microscopy (STM) tip applying a localized potential. The purple spheres at the North Pole and South Pole denote a pair of entangled electrons, with green arrows indicating the spin orientations of each electron. b The orbital angular momentum l as functions of crossover temperature Tc for different electron densities ρe. Green solid and dotted lines correspond to InSb with ρe = 1013cm−2 and 1011cm−2, respectively; purple dashed and dash-dotted lines correspond to GaAs with the same electron densities. c The radius R as functions of crossover temperature Tc for different ρe. Source data are provided in the Supplementary Data.
