Multiple photon field-induced topological states in bulk HgTe.

Strong light-matter interactions can be exploited to modify properties of quantum materials both in and out of thermal equilibrium. Recent studies suggest that electromagnetic fields in photonic structures can hybridize with condensed matter systems, resulting in photon field-dressed collective quantum. Here, we show that photon fields in photonic structures, including optical cavities and waveguides, induce emergent topological phases in solids through polarization-mediated symmetry-breaking mechanisms. Using state-of-the-art quantum electrodynamic density functional theory calculations, we demonstrate that strong light-matter coupling can reconfigure both the electronic and ionic structures of HgTe, driving the system into Weyl, nodal-line, or topological insulator phases. These phases depend on the relative orientation of the sample in the coupling strength. In contrast with laser-driven phenomena, the photon field-induced symmetry breaking arises from steady-state photon-matter hybridization, enabling multiple robust topological states to emerge. Our study demonstrates that vacuum fluctuations in photonic structures can be used to engineer material properties and realize rich topological phenomena in quantum materials on demand.