Dark matter is one of the greatest mysteries in physics. It interacts via gravity and composes most of our universe, but its elementary composition is unknown. We search for nongravitational interactions of axion-like dark matter with atomic spins using a precision quantum detector. The detector is composed of spin-polarized xenon gas that can coherently interact with a background dark matter field as it traverses through the galactic dark matter halo. Conducting a 5-month-long search, we report on the first results of the Noble and Alkali Spin Detectors for Ultralight Coherent darK matter (NASDUCK) collaboration. We limit ALP-neutron interactions in the mass range of 4 × 10 −15 to 4 × 10 −12 eV/ c 2 and improve upon previous terrestrial bounds by up to 1000-fold for masses above 4 × 10 −13 eV/ c 2 . We also set bounds on pseudoscalar dark matter models with quadratic coupling.

Nuclear spins of noble-gas atoms are exceptionally isolated from the environment and can maintain their quantum properties for hours at room temperature. Here we develop a mechanism for entangling two such distant macroscopic ensembles by using coherent (i.e. classical) light input. The interaction between the light and the noble-gas spins in each ensemble is mediated by spinexchange collisions with alkali-metal spins, which are only virtually excited. The relevant conditions for experimental realizations with 3 He or 129 Xe are outlined.

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