Probing GHz gravitational waves with graviton–magnon resonance

A novel method for extending the frequency frontier in gravitational wave observations is proposed. It is shown that gravitational waves can excite a magnon. Thus, gravitational waves can be probed by a graviton–magnon detector which measures resonance fluorescence of magnons. Searching for gravitational waves with a wave length λ λ by using a ferromagnetic sample with a dimensionl, the sensitivity of the graviton–magnon detector reaches spectral densities, around 5.4 × 10⁻²² × (l/λ /2π )⁻² \ [Hz-1/2] 5.4×10-22×(lλ/2π)-2[Hz-1/2] at 14 GHz and 8.6 × 10⁻²¹ × (l/λ /2π )⁻² \ [Hz-1/2] 8.6×10-21×(lλ/2π)-2[Hz-1/2] at 8.2 GHz, respectively.