Advancing Rydberg atom-based axion detection

Dark matter is the name that we give to the 84% of matter in the universe that interacts via gravity but negligibly with any of the other known forces. One compelling model for dark matter is the axion, as it simultaneously solves the existence of dark matter and the strong CP problem in QCD. The traditional axion experiment is called a haloscope, which consists of a strong magnetic field, a microwave cavity to resonantly enhance the converted photon, and a low-noise amplifier to enhance the inevitably tiny signal. This proceedings discusses the development of RAY (Rydberg atoms for Axions at Yale), a single photon detector that can be integrated into a standard haloscope. A major challenge of axion searches at higher masses is that the time required becomes increasingly long because of lower signal and increased quantum noise when using a standard haloscope. Eliminating this quantum noise can be accomplished with single photon counting using Potassium-39 Rydberg atoms. Using a beam of Rydberg atoms to detect the photons generated through the Primakoff effect would render the axion search at higher masses (> 50 µeV) tractable. We have done initial work towards this goal using electromagnetically-induced transparency. Depending on the haloscope cavity this scheme is attached to, we may be able to measure masses in the range of 20-30 GHz at KSVZ sensitivity in 5 years in a standard tunable cavity, or 10-50 GHz at KSVZ sensitivity in 5 years in a resonator with volume independent of frequency.