Negative permeability in a Λ-type three-level atomic vapor

A new approach is suggested to realize negative magnetic permeability that follows directly from quantum mechanics. It is shown that a Delta-type three-level atomic system with proper atomic parameters can give rise to striking magnetic responses, which could exhibit negative permeability in an optical frequency band. Both steady and transient behaviors of the magnetic permeability in the atomic vapor are studied. The present negative-permeability vapor could be mixed with a quantum coherent vapor whose electric permittivity is negative. Such a mixed vapor may give an isotropic left-handed vapor medium at the atomic-scale level.