Prospects for Axion Dark Matter Searches at LISA-like Interferometers

Axion or axion-like particle has been one of the leading candidates for dark matter. Due to its tiny coupling with photon, axion dark matter in the background can induce distinct phase velocities of light with different parity, an effect known as axion-induced birefringence. Here, we propose a modification to the polarization state of the inter-spacecraft laser link in LISA-like interferometers in space to make them sensitive to this birefringence effect. We discuss the prospects of using Sagnac combinations to search for axion dark matter and derive the corresponding sensitivity. With this setup, we show that next-generation laser interferometers in space would have great sensitivities on the axion-photon coupling with axion mass around \(10^{-19}~\text{eV}\sim 10^{-14}~\text{eV}\).