http://arxiv.org/abs/2105.02005
We introduce the concept of impedance matching to axion dark matter by posing the question of why axion detection is difficult, even though there is enough power in each square meter of incident dark-matter flux to energize a LED light bulb. We show that a small axion-photon coupling does not in itself prevent an order-unity fraction of the dark matter from being absorbed through an optimal impedance match. We further show that, since the axion mass is unknown, the photon-electron coupling across a frequency-integrated impedance match must be considered to determine constraints on power coupled from axion dark matter. Using conservation of energy statements derived from the equations of axion electrodynamics, we demonstrate stringent limitations on absorbed power in linear, time-invariant, passive receivers. We discuss the results in the context of recent works constraining axion search sensitivity that conduct a broad first-principles optimization of receivers subject to the Standard Quantum Limit on phase-insensitive amplification.
S. Chaudhuri
Thu, 6 May 21
13/55
Comments: 13 pages, 3 figures, plus references and appendices
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