Precision Frequency Metrology for Axion Searches

It is demonstrated how precision frequency metrology can overcome critical challenges in axion dark matter searches. Using a generalization of the standard axion haloscope approach onto a case with two resonant modes, a transfer function from axion signal to resonant mode phase fluctuations is derived. The method is not only sensitive enough in principle to achieve the predicted model bands, but also remove the main complications such as the need for strong magnetic fields, large cavity volumes, and quantum sensors.