  We propose novel quantum antennas and metamaterials with strong magnetic
response at optical frequencies. Our design is based on the arrangement of
natural atoms with only electric dipole transition moments at distances smaller
than a wavelength of light but much larger than their physical size. In
particular, we show that an atomic dimer can serve as a magnetic antenna at its
antisymmetric mode to enhance the decay rate of a magnetic transition in its
vicinity by several orders of magnitude. Furthermore, we study metasurfaces
composed of atomic bilayers with and without cavities and show that they can
fully reflect the electric and magnetic fields of light, thus, forming nearly
perfect electric/magnetic mirrors. The proposed quantum metamaterials can be
fabricated with available state-of-the-art technologies and promise several
applications both in classical optics and quantum engineering.
