Superluminal propagation via coherent manipulation of the Raman gain process

Abstract

We present a method of manipulating the Raman process by using a coherent control field which leads to splitting of the Raman gain peak into a doublet and anomalous dispersion in the region between the gain peaks. We show how the region of almost no Raman gain and strong anomalous dispersion is ideally suited for producing superluminal propagation. In particular, we show that the group index for a $^{23}\mathrm{Na}$ condensate could be in the range $\ensuremath{-}{10}^{3}$ to $\ensuremath{-}{10}^{4}$.