Nonlinear effects in resonance conversion as a test of QED

Various phenomena such as hyperfine shift of ²⁰⁹Bi⁸²⁺, nuclear decay of ²²⁹Th, and ¹⁶⁹Yb⁶⁹⁺ are considered as cross-invariant channels of the internal conversion process from the viewpoint of testing QED. The way of accelerating nuclear decay in a laser field through merging nuclear and laser photons is discussed. Discovering this fundamental process would give a convincing test of both QED along with our experimental capabilities.