Phys. Rev. Lett. 116, 165502 (2016)

Although research in metamaterials has witnessed a rapid growth in recent years, the presence of large optical losses and structural imperfections are still unsolved issues. In an attempt to address such pressing challenges, Pankaj Jha and co-workers in the US and Saudi Arabia have turned to cold atoms in optical lattices to design a new architecture for metamaterials. In their proposed atomic lattice quantum metamaterial, off-resonant and blue-detuned laser beams trap ultracold atoms exhibiting an optical response that can be tuned thanks to two coherent drive fields. The authors theoretically demonstrate that they can engineer a system where the permittivity near an atomic resonance is negative at the lattice sites, and the vacuum between adjacent sites acts as a dielectric medium. Careful manipulation of the parameters that characterize the driving lasers is shown to allow for the complete cancellation of optical absorption, whereas turning off the external coherent fields produces non-zero values for the imaginary part of the permittivity. Further, Jha and collaborators highlight how their scheme can lead to optical lattice metamaterials with hyperbolic dispersion. They predict that, in principle, the approach can be extended to 2D and 3D lattices.