A dark matter detector based on ytterbium atom interferometry

We are constructing a Ytterbium atom interferometer to search for ultralight dark matter. This device will be sensitive to scalar, pseudoscalar, and vector dark matter couplings in the frequency range of 10^-8 Hz to 10 Hz. Here we present the experimental design and the projected sensitivities for three independent detection channels. The apparatus will consist of a source of ultracold Yb atoms and a magnetically shielded atomic fountain, enabling coherence times of at least 0.5 s. Sensitivity to scalar dark matter will be obtained through a frequency ratio measurement of two electronic transitions. This measurement is projected to improve on previous searches by a factor of ~100 over five orders of magnitude in the dark matter particle mass. A comparison of the differential acceleration of two Yb isotopes will provide a search for vector dark matter at sensitivities comparable to existing limits, and a frequency ratio measurement of electronic transitions with Δm_I = ± 1 will be sensitive to spin torque induced by pseudoscalar dark matter. The experiments performed in this system will pave the way for future dark matter searches in long-baseline interferometers such as MAGIS-100.