Conical intersections for light and matter waves

TL;DR

This paper reviews the design, theory, and applications of two-dimensional lattices with conical intersections, highlighting their potential in advanced photonic and quantum systems.

Contribution

It provides a comprehensive overview of conical intersections in various lattice systems, emphasizing new types with higher pseudospin and their diverse applications.

Findings

Higher order conical intersections with bosonic pseudospin are achievable.

Engineered lattices enable novel applications like zero-index metamaterials.

Conical intersections facilitate quantum simulation of relativistic phases.

Abstract

We review the design, theory, and applications of two dimensional periodic lattices hosting conical intersections in their energy-momentum spectrum. The best known example is the Dirac cone, where propagation is governed by an effective Dirac equation, with electron spin replaced by a "fermionic" half-integer pseudospin. However, in many systems such as metamaterials, modal symmetries result in the formation of higher order conical intersections with integer or "bosonic" pseudospin. The ability to engineer lattices with these qualitatively different singular dispersion relations opens up many applications, including superior slab lasers, generation of orbital angular momentum, zero-index metamaterials, and quantum simulation of exotic phases of relativistic matter.