Enhanced Axion-Photon Conversion via Seeded Photons instead of Resonant Cavities for Short-Pulse Axion Detection

Abstract: We propose a seeded axion-photon conversion scheme to enhance the sensitivity of light-shining-through-wall (LSW) experiments for axion detection, where the axions are generated from short pulse lasers and the usual resonant cavity is not applicable. By injecting a small, coherent seed electromagnetic field (EM field) into the axion-photon conversion region, the axion-induced EM field can constructively interfere with the seed field, amplifying the regenerated photon number beyond the unseeded case. Starting from the axion-modified Maxwell equations, we derive the axion-photon conversion probability and show how an initial seed field boosts the final photon amplitude. The relative phase between the seed field and the axion field can cause constructive or destructive interference, though the measurable quantity is the net photon number variation. We evaluate the expected signal enhancement, signal-to-noise considerations (including seed shot noise), and the potential improvement in coupling sensitivity. Compared to a standard LSW setup, the seeded scheme can achieve orders-of-magnitude higher photon yield per axion, potentially surpassing resonance-enhanced experiments in certain parameter regimes. This approach offers a promising route to extend the reach of laboratory axion searches, especially for the case where the resonant cavities are impractical.