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, $g_{\mathrm{a}\gamma }$, reaches $g_{\mathrm{a}\gamma }\simeq 8\times {10}^{-13}{\mathrm{GeV}}^{-1}(4\times {10}^{-14}{\mathrm{GeV}}^{-1})$ at the axion mass $m\simeq 3\times {10}^{-13}\mathrm{eV}$ ($2\times {10}^{-15}\mathrm{eV}$) and remains at around this sensitivity for three orders of magnitude in mass. Furthermore, its sensitivity has a sharp peak reaching $g_{\mathrm{a}\gamma }\simeq {10}^{-14}{\mathrm{GeV}}^{-1}(8\times {10}^{-17}{\mathrm{GeV}}^{-1})$ at $m=1.563\times {10}^{-10}\mathrm{eV}$ ($1.563\times {10}^{-11}\mathrm{eV}$). This sensitivity can be achieved without losing any sensitivity to gravitational waves.

Figure 1

Schematic of experimental setup for the axion search with a linear optical cavity. FI, Faraday isolator; HWP, half wave plate; PBS, polarizing beam splitter; PD, photodetector; BD, beam dump. Signal is detected in detection port (a) and (b). Components for phase measurement are not shown. The polarization of incident light is arbitrary only if it is linear polarization. Two PBSs in FI are placed, rotated by 45 degrees, along the optical path.

Figure 2

Sensitivity comparison of the several parameter sets shown in Table 1. Although the higher mass range seems to be filled, they have sensitivity peaks at mass of $m=\pi (2N-1)/L(N\in \mathbb{N})$. The gray and green band express the current limit provided by CAST [5] and the cosmic ray observations of SN1987A [14]. The red dashed line is a sensitivity curve of one proposed experiment using optical ring cavity with optimistic parameters [26].