'Toward High-Mass Axion Searches with Plasma Haloscopes.'

This is a multi-institution, multidisciplinary pathfinder program to develop quantum sensing technologies and novel techniques to search for axion dark matter. The research program extends the axion search capabilities in HEP to a range between 80–200 µeV, corresponding to photons at 20–50 GHz. Recent calculations for a mass range predicated by post-inflationary axion generation scenarios, such as those using adaptive mesh simulations, point to axions around 40–180 µeV, corresponding to photon frequencies between 10 – 45GHz. 'Illuminating the hidden universe' is one of the three scientific themes of the 2023 Particle Physics Project Prioritization Panel (P5) report, a 10-year strategic plan for US particle physics in the context of a 20-year global vision. 'Determining the nature of dark matter' is the science driver for this work and one of the central goals of the cosmic frontier in HEP. The QCD axion and axion-like particles are well-motivated dark matter candidates that address the strong CP problem. These wave-like dark matter candidates possess masses less than 1 eV and require novel approaches in quantum sensing. The project will develop technologies to further axion search capabilities in HEP. The program extends and capitalizes on the advances made with support from the previous QuantISED program. This pathfinder program will bring new technologies to HEP and pave a path toward a discovery-class high-mass axion haloscope. The research program will focus on developing three key technologies that take advantage of the recent progress in quantum sensing and are crucial in extending the axion mass region up to 80–200 µeV, corresponding to 20–50 GHz. This mass region is currently not accessible by the HEP community. With this research program, we will 1) develop resonators based on tunable superconducting metamaterials; 2) develop single-photon readout using Rydberg atoms; and 3) extend the frequency range of existing superconducting circuit-based photon readout, pairing Josephson-parametric amplifiers to form a squeezed state receiver at higher photon frequencies and develop photon counting techniques with superconducting circuits. Additionally, if found to be suitable, the above technologies will be deployed in an initial science run.