Search for exotic parity-violation interactions with quantum spin amplifiers.

Quantum sensing provides sensitive tabletop tools to search for exotic spin-dependent interactions beyond the standard model, which have attracted great attention in theories and experiments. Here, we develop a technique based on Spin Amplifier for Particle PHysIcs REsearch (SAPPHIRE) to resonantly search for exotic interactions, specifically parity-odd spin-spin interactions. The present technique effectively amplifies exotic interaction fields by a factor of about 200 while being insensitive to spurious magnetic fields. Our studies, using such a quantum amplification technique, explore the parity-violation interactions mediated by a new vector boson in the challenging parameter space (force range between 3 mm and 1 km) and set the most stringent constraints on axial-vector electron-neutron couplings, substantially improving previous limits by five orders of magnitude. Moreover, our constraints on axial-vector couplings between nucleons reach into a hitherto unexplored parameter space. The present constraints complement the existing astrophysical and laboratory studies on potential standard model extensions.