Superluminal light propagation assisted by Zeeman coherence.
We have observed a dispersionlike absorption (or gain) spectrum at the D1 transition in a Rb vapor cell filled with a buffer gas, due to Zeeman coherence of the ground states in a double Lambda configuration. Meanwhile, we have also observed superluminal pulse propagation. It is experimentally demonstrated that the front speed of a light pulse still equals the light speed c in vacuum, although the group velocity of the light pulse is(-2.2+/-0.6) x 10(4) m/s.
He
Huijuan
H
Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800, China.
Hu
Zhengfeng
Z
Wang
Yuzhu
Y
Wang
Ligang
L
Zhu
Shiyao
S