Quantum Science and the Search for Axion Dark Matter

The dark-matter puzzle is one of the most important open problems in modern physics. The ultralight axion is a well-motivated dark-matter candidate, conceived to resolve the strong-CP problem of quantum chromodynamics. Numerous precision experiments are searching for the three nongravitational interactions of axionlike dark matter. Some of the searches are approaching fundamental quantum limits on their sensitivity. This Perspective describes several approaches that use quantum engineering to circumvent these limits. Squeezing and single-photon counting can enhance searches for the axion-photon interaction. Optimization of quantum spin-ensemble properties is needed to realize the full potential of spin-based searches for the electric dipole moment and the gradient interactions of axion dark matter. Several metrological and sensing techniques, developed in the field of quantum information science, are finding natural applications in this area of experimental fundamental physics.

Automated summary

The dark-matter puzzle is a significant open problem in modern physics, and the ultralight axion is a well-motivated candidate for dark matter. Various precision experiments are searching for the non-gravitational interactions of axionlike dark matter, with some nearing the quantum limits of sensitivity. This Perspective discusses quantum engineering approaches to overcome these limits and describes the utilization of metrological and sensing techniques from quantum information science in experimental physics.