Polariton Spectrum
Rabi splitting 2g: – THz
Upper polariton: – THz
Lower polariton: – THz
Cooperativity C: –
Regime: –
When coupling g exceeds damping rates, normal modes hybridize into magnon-polaritons. Anti-crossing gap = 2g (vacuum Rabi splitting). Cooperativity C = 4g²/(κ_m·κ_c) > 1 = strong coupling. Realized in YIG (yttrium iron garnet) at GHz–THz. Applications: quantum transducers, magnonic circuits.