FAST LIGHT

A pulse propagates with a group velocity which is not bound by the speed of light c, hence it can be higher than c, or even negative.

GAS : "Gain-assisted superluminal light propagation," Nature 406, 277-9 (2000).

 see Group Velocity in Dispersive Media (1Mb movies!)

• L. J. Wang, A. Kuzmich, and A. Dogariu, “Gain-assisted superluminal light propagation,” Nature 406, 277-9 (2000)
• A. Dogariu, A. Kuzmich, and L. J. Wang, "Transparent Anomalous Dispersion and Superluminal Light Pulse Propagation at a Negative Group Velocity," Phys. Rev. A (Atomic, Molecular and Optical Physics), 63 (5), 053806-12, (2001).
• A. Dogariu, A. Kuzmich, H. Cao, and L. J. Wang, "Superluminal light pulse propagation via rephasing in a transparent anomalously dispersive medium,"   Optics Express 8, 344-350 (2001).
• A. Kuzmich, A. Dogariu, L. J. Wang, P. W. Milonni, and R. Y. Chiao, "Signal velocity, causality, and quantum noise in superluminal light pulse propagation," Phys. Rev. Lett. 86, 3925 (2001).
• H. Cao, A. Dogariu, and L. J. Wang, “Negative group delay and pulse compression in superluminal pulse propagation,” IEEE J. Select. Topics Quantum Electron., Vol. 9, No. 1, 52 (2003).