3

Topological states and flat bands in exactly solvable decorated Cayley trees

We derive the full spectrum of decorated Cayley trees that constitute tree analogs of selected two-dimensional Euclidean lattices; namely of the Lieb, the double Lieb, the kagome, and the star lattice. The common feature of these Euclidean lattices …

Superconductivity in hyperbolic spaces: Cayley trees, hyperbolic continuum, and BCS theory

We investigate $s$-wave superconductivity in negatively curved geometries, focusing on Cayley trees and the hyperbolic plane. Using a self-consistent Bogoliubov--de Gennes approach for trees and a BCS treatment of the hyperbolic continuum, we …

Topological non-Abelian Gauge Structures in Cayley-Schreier Lattices

Recently, novel crystalline constructions known as Cayley-Schreier lattices have been suggested as a platform for realizing arbitrary gauge fields in synthetic crystals with real hopping amplitudes. We show that Cayley-Schreier lattices can naturally …

Superconductivity in hyperbolic spaces: Regular hyperbolic lattices and Ginzburg-Landau theory

We study $s$-wave superconductivity in hyperbolic spaces using the Bogoliubov-de Gennes theory for discrete hyperbolic lattices and the Ginzburg-Landau theory for the continuous hyperbolic plane. Hyperbolic lattices maintain a finite fraction of …

Delicate Wannier Insulators

The defining feature of topological insulators is that their valence states are not continuously deformable to a suitably defined atomic limit without breaking the symmetry or closing the energy gap. When the atomic limit is given by symmetric …