Silicon mirrors show quantum light-matter coupling in picoseconds

Researchers have achieved strong light-matter coupling with a switch-on time of just a few picoseconds, enabling on-demand triggering of this phenomenon for the first time. The team demonstrated this dynamic activation within a terahertz Fabry-Pérot cavity using crystalline α-lactose powder. By photoexciting silicon-based cavity mirrors, they induced a spectral shift and linewidth narrowing, substantially increasing the Q-factor, to tune the cavity into resonance with the material's vibrations. This ability to actively trigger strong coupling at picosecond timescales offers new opportunities to study its dynamics and guide chemical reactivity. Silicon's ability to rapidly alter its optical properties when stimulated with light has enabled the creation of a…