Improving Dark Matter Axion Searches with Active Resonators
  Axions are a well motivated candidate for dark matter. The most sensitive
experiments searching for dark matter axions rely on the coupling of axions to
the electromagnetic resonances of a microwave cavity immersed in a strong
magnetic field. The sensitivity of the experiment is proportional to the Q of
the resonance that is coupled to axions. To date, the resonators used in axion
searches have all been passive, with Qs limited by power loss in the cavity
walls. I propose the use of active feedback resonators to increase the Q of
microwave cavity axion dark matter experiments by several orders of magnitude.
This should allow experiments to significantly increase the rate at which they
can test potential axion masses and couplings.
