Electromagnetic high-frequency gravitational wave detection

Ultra-high frequency gravitational waves in the MHz to THz regime promise a unique possibility to probe the very early universe, particle physics at very high energies and exotic astrophysical objects - but achieving the sensitivity required for detection is an immense challenge. This is a brief summary of recent progress in electromagnetic high-frequency gravitational wave searches, which are based on classical electromagnetism in a space-time perturbed by gravitational waves. A particular focus is given to synergies with axion searches and atomic precision measurements. This article was prepared as proceedings for Moriond EW 2023.