Figure 4 - uploaded by Mathew Elman
Content may be subject to copyright.
1: Achiral Structure Showing Isolated 5-fold Degeneracy at R P =0, (x, y, z)=(0.227, 0.227, 0.227), r=0.111, ε=16. (a) shows the bulk band structure with the upper and lower hyperconic bands coloured red and bands are blue. The green band corresponds to the 0 eigenvalue flat mode. Isolated topological surface states may occur between the upper red band and green band. (b) shows the supercell calculation for the surface states, the green region corresponds to the bulk. The white region is the pseudo gap where the surface states occur, shown by the red (TM) and blue (TE) bands that enter the white region.
Source publication
In this thesis, design principles developed through group and perturbation theory are used to induce deterministic non-trivial topology at the high symmetry points of the Brillioun Zone, such as a Pseudo Weyl Point. A symmetry induced Pseudo Weyl Point is a deterministic threefold degenerate equivalent to an accidental Weyl point at an arbitrary po...
Citations
... They are not independent and form a trinity: Application of any pair yields the remaining operation, for exampleÔ TRÔRec =Ô Herm . For the unitary spatial symmetriesĝ, we show in [21] that it suffices for the permutation elements to satisfy ...
Recent interest in optical analogues to the quantum spin Hall and quantum valley Hall effects is driven by the promise to establish topologically protected photonic edge modes at telecommunication and optical wavelengths on a simple platform suitable for industrial applications. While first theoretical and experimental efforts have been made, these approaches so far both lack a rigorous understanding of the nature of topological protection and the limits of backscattering immunity. We here use a generic group theoretical methodology to fill this gap and obtain general design principles for purely dielectric two-dimensional topological photonic systems. The method comprehensively characterizes possible 2D hexagonal designs and reveals their topological nature, potential and limits.
