Coupling of an Open Cavity to a Microwave Beam: A Possible New Scheme for Detecting High-Frequency Gravitational Waves

Abstract

We propose a new device for detecting high‐frequency gravitational waves (HFGWs) in the GHz band, which consists of a high‐quality‐factor open microwave cavity and a Gaussian beam (GB) passing through a static magnetic field in free space. Essentially this effect is an inverse Gertsenshtein effect in which HFGWs are converted into electromagnetic (EM) waves when passing through a static magnetic field. Under the synchro‐resonance condition (with the frequency of the EM and HFGW the same) using the very high sensitivity of fractal membranes to the polarization directions of the EM normal modes (standing waves) in the cavity, the perturbative EM fields stored in the cavity can be converted into an instantaneous EM power flux (perturbative photon flux or PPF for detection) in the free space, which would be superimposed on the perturbative EM fields generated by the HFGWs in the coupling space of the Gaussian beam and the static magnetic field. The total PPF caused by such resonant effect of HFGWs will reach a detector or tuned receiver of the microwave photons and provide for HFGW detection. This paper also discusses detection condition for stochastic high‐frequency relic GW background (HFRGWs) and the detectability of HFGWs generated in laboratory, and provides a review of the systems selection capabilities and identifies crucial noise issues.