Experimental observation of Rabi splitting in effective near-zero-index media in the microwave regime

We report the observation of a strong coupling between an artificial "atom" and localized interface mode in the microwave regime. Transmittance is experimentally measured for the effective near-zero-index paired structures containing ε -negative and μ -negative materials made of composite right- and left-handed transmission lines. When the atom is embedded in the interface, because of the strong coupling between the atom and the interface mode, a Rabi splitting of 0.12 GHz is observed, which is in good agreement with numerical simulations. Different from the usual Rabi splitting observed in conventional cavities, the splitting modes in the effective zero-index media are invariant with the scaling change of the length.