Multicolor coherence-induced negative refraction in three-level atomic system

Electromagnetically induced negative refraction in an atomic system with spontaneously generated coherence

Negative refraction without absorption via both coherent and incoherent fields in a four-level left-handed atomic system

Electromagnetically induced negative refractive index in a V-type four-level atomic system

Left-Handedness in a Four-Level Atomic System: Quantum Coherence, Electromagnetically Induced Transparency and Negative Refraction

Microwave-induced coherence effects in refractive index of a V-type three-level atom

Large index of refraction without absorption via decay-induced coherence in a three-level V system