Terahertz cavities engineer attractive interactions in bilayer graphene

Terahertz cavity photons mediate tunable attractive interactions in bilayer graphene, reorganizing interband transitions into an exciton-like bound state. Using a broadband terahertz microscope integrated with dual-gated 2D materials in a THz cavity, researchers observe tunable bandgaps and ultrastrong coupling (g/ωc ≈ 0.4) with a cavity-induced resonance that persists across a wide temperature range, pointing to a platform for exploring hybrid light–matter phases in 2D quantum materials.