Quantum-enhanced interferometry for axion searches

Abstract

We propose an experiment to search for axions and axionlike particles in the galactic halo using quantum-enhanced interferometry. This proposal is related to the previously reported ideas [W. DeRocco and A. Hook, Phys. Rev. D 98, 035021 (2018); I. Obata, T. Fujita, and Y. Michimura, Phys. Rev. Lett. 121, 161301 (2018); H. Liu, B. D. Elwood, M. Evans, and J. Thaler, Phys. Rev. D 100, 023548 (2019)] but searches for axions in the mass range from ${10}^{\ensuremath{-}16}\text{ }\text{ }\mathrm{eV}$ up to ${10}^{\ensuremath{-}8}\text{ }\text{ }\mathrm{eV}$ using two coupled optical cavities. We also show how to apply squeezed states of light to enhance the sensitivity of the experiment similar to the gravitational-wave detectors. The proposed experiment has a potential to be further scaled up to a multi-km long detector. We show that such an instrument has a potential to set constrains of the axion-photon coupling coefficient of $\ensuremath{\sim}{10}^{\ensuremath{-}18}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$ for axion masses of ${10}^{\ensuremath{-}16}\text{ }\text{ }\mathrm{eV}$ or detect the signal.