Vacuum induced transparency in metamaterials.

For the cavity-based electromagnetically induced transparent (EIT), as the coherent driving field is enhanced by the optical cavity, the weak probe field can propagate through the atomic ensemble without absorption even if the driving field is weak. The extreme case of vacuum in the cavity is called "vacuum-induced transparency" (VIT) to distinguish it from the cavity EIT. Here we construct a new kind of cavity made of Metamaterials, i.e. ε-negative (EN) and μ-negative (MN) slabs, and study the VIT phenomena of the atomic ensemble doped within it. When the impedances of the MN and EN slabs are matched to each other and the dissipation of the material is small, it behaves as a surface plasmon cavity with a huge Q factor. And the VIT phenomenon in this cavity appears. By adjusting the position of atoms, the coupling strength between the atom and the structure could be changed. Two kinds of extremes of VIT, the coherent population trapping (CPT) and the Autler-Townes splitting (ATS), can be achieved in this system easily. Our proposal could be used in the realization of ultra-strong coupling and integrated devices on quantum memory or optical switch.