Axion Dark Matter Search with Interferometric Gravitational Wave Detectors.

Axion dark matter differentiates the phase velocities of the circular-polarized photons. In this Letter, a scheme to measure the phase difference by using a linear optical cavity is proposed. If the scheme is applied to the Fabry-Pérot arm of Advanced-LIGO-like (Cosmic-Explorer-Like) gravitational wave detector, the potential sensitivity to the axion-photon coupling constant, g_{aγ}, reaches g_{aγ}≃8×10^{-13}  GeV^{-1}(4×10^{-14}  GeV^{-1}) at the axion mass m≃3×10^{-13}  eV (2×10^{-15}  eV) and remains at around this sensitivity for three orders of magnitude in mass. Furthermore, its sensitivity has a sharp peak reaching g_{aγ}≃10^{-14}  GeV^{-1}(8×10^{-17}  GeV^{-1}) at m=1.563×10^{-10}  eV (1.563×10^{-11}  eV). This sensitivity can be achieved without losing any sensitivity to gravitational waves.