We propose a resonant detector architecture for High-Frequency Gravitational Waves (HFGW) in the GHz band, utilizing a microwave bridge interferometer topology. Unlike prior proposals relying on the inverse Gertsenshtein effect (photon conversion), which scales quadratically with strain (P ∝ h2 ), the “Rebellon Bridge” exploits the geometric modulation of the cavity boundary conditions to achieve linear sensitivity (V ∝ h). The system employs a tri-axial superconducting cavity arrangement fed by a cryogenic sapphire oscillator. A passing gravitational wave induces a quadrupole deformation of the cavity geometry, disrupting the destructive interference condition atthe readout port. We present a noise budget analysis demonstrating that with a cavity Quality Factor of Q ∼ 1010 and millikelvin cooling, the √ system can overcome thermal and phase noise floors to reach strain sensitivities of h ∼ 10−22 / Hz, potentially opening the window to primordial cosmological sources.
Manuel Rebellón (2026) studied this question.