Terahertz cavity hybridization of collective proteins vibrations
Hybrid light-matter states have transformed photonics, yet their realization with driven collective vibrations in biological systems remains an open challenge. Here we show that optically pumped R-phycoerythrin proteins at room temperature support coherent sub-terahertz vibrational modes consistent with Frohlich condensation, and that these modes hybridize with confined terahertz cavity photons in a microfluidic cavity platform. The resulting spectra exhibit a resolved doublet, power- and concentration-dependent redistribution of spectral weight, and linewidth narrowing indicative of cavity-modified dissipation. Quantitative analysis reveals collective square-root of N-scaling of the coupling strength, with cooperativity and splitting-to-linewidth ratios exceeding unity, consistent with the onset of strong collective coupling driven by the vibrational molecular mode. A microscopic nonequilibrium analysis further indicates that the relaxation timescale toward the Frohlich polariton state is on the order of 1-10 microseconds. These findings identify terahertz cavities as a platform for stabilizing and controlling collective molecular vibration dynamics and open opportunities for cavity-engineered vibrational spectroscopy, label-free biosensing and photonic control of energy transport in complex biomolecular systems.