Symmetry in magnetoelectric electromagnetism and magnetoelectric meta-atoms

While in electromagnetism we have space-time symmetry, magnetoelectric (ME) processes are characterized by space-time symmetry breaking. Our goal is to show that quantum vacuum fields with both time reversal and space inversion symmetry breaking (so-called ME fields) can be observed in subwavelength regions of electromagnetic (EM) radiation. The sources of ME fields are ME meta-atoms, subwavelength elements made of magnetic insulators, where the dynamical ME behavior is due to modulations and topological coupling of magnetization and electric polarization. The interaction between EM and ME systems occurs through virtual structures, ME virtual photons. Experimentally, ME quantum vacuum states can be detected in a microwave cavity. The topic of these studies concerns fundamental aspects of ME quantum electrodynamics (MEQED).