  We develop a new spectroscopic method to quickly and intuitively characterize
the coupling of two microwave-photon-coupled semiconductor qubits via a
high-impedance resonator. Highly distinctive and unique geometric patterns are
revealed as we tune the qubit tunnel couplings relative to the frequency of the
mediating photons. These patterns are in excellent agreement with a simulation
using the Tavis-Cummings model, and allow us to readily identify different
parameter regimes for both qubits in the detuning space. This method could
potentially be an important component in the overall spectroscopic toolbox for
quickly characterizing certain collective properties of multiple cavity QED
coupled qubits.
