Topology by Strong Light-Matter Coupling and Electrical Control

Quantum geometry, often governed by symmetries of materials, has emerged as a new framework for transport and nonlinear phenomena in novel states of matter. Photonic systems are facile for realizing spatial geometry and symmetries by design; they have provided a fertile ground for exploring non-trivial quantum geometries where time reversal symmetry is preserved. But achieving topologically non-trivial bands for photonic systems remains challenging due to the requirement of breaking the time-reversal symmetry with magnetic materials or large magnetic fields. A promising approach is to integrate exciton materials and form exciton-photon hybrid modes of polariton modes in the strong coupling regime, which allows efficient control of the time-reversal symmetry via the excitonic medium. 

In this talk, we will discuss two classes of photonic-crystal polariton systems that support the formation of Chern bands beyond Dirac cones, readily allowing higher-order Chern bands and topological gap sizes two orders of magnitude larger than previously possible. We will also discuss experimental implementations of such systems where large topological gaps and distributions of quantum geometry can be electrically controlled.