In a major breakthrough, scientists control light propagation in photonic chips: "We're very excited about this. We've engineered and observed a metamaterial with zero refractive index,' said Kocaman. 'What we've seen is that the light disperses through the material as if the entire space is missing. The oscillatory phase of the electromagnetic wave doesn't even advance such as in a vacuum — this is what we term a zero-phase delay...'"
...They... cascaded the negative index medium with a positive refractive index medium so that the complete nanostructure behaved as one with an index of refraction of zero.