June 19, 2012
      
                  
        
  Author(s)
  Ryan T. Glasser,   Ulrich  Vogl,   Paul D. Lett
 
       
            
    
    
        Optical pulse propagation with group velocities larger than the speed of light in vacuum, c, or negative, have been demonstrated theoretically and experimentally in a variety of systems [15]. The anomalous dispersion required for generating fast light