Exploration of new experimental strategies for the detection of ultralight dark matter : laboratory searches on ground and in space

Abstract: Ultralight dark matter (ULDM), as a class of low mass (< 1 eV) dark matter (DM) candidates, is a compelling alternative to historically dominant models such as WIMPs and has recently gained significant attention in the scientific community. In this thesis, we study various experimental schemes for the direct detection of ULDM, both on ground and in space. More precisely, we propose a theoretical modeling of current and futuristic experiments, and we derive an estimation of their respective sensitivity. We mainly concentrate on three distinct phenomenologies. The first one is the coupling between a DM U(1) field, known as the dark photon (DP), and electromagnetism, which induces a small electric field oscillating at the DP Compton frequency. We study how to detect this electric field using atoms inside a cavity and through dish antennas. The second main phenomenology considered in this thesis is the oscillation of rest mass and transition frequencies of atoms and test masses. These oscillations could be produced by the non-universal coupling of standard matter with a scalar ULDM candidate (dilaton or axion-like particle). We study how to detect such couplings in classical tests of the universality of free fall (UFF), atom interferometry and using LISA. Finally, we study the effect of vacuum birefringence and dichroism induced by the coupling between axions and photons, and how it could be detected with optical cavities, fibers, and LISA.