超光速群速度与信息传输的有效速度  

Superluminal Group Velocity and Effective Velocity of Information Transfer

作　　者：郭奇志[1] 谭维翰[1] 

机构地区：[1]上海大学物理系,上海200444

出　　处：《光学学报》2007年第2期344-349,共6页Acta Optica Sinica

基　　金：上海市重点学科建设项目(T0104)资助课题

摘　　要：研究了反常色散介质中脉冲形变对超光速群速度的影响,发现即使光脉冲完全不产生形变群速度仍会超过真空中的光速。但波包的群速度并不等同于信号的传输速度,采用信息论方法,定义了信号的有效传输速度,并用于解释WKD(Wang,Kuzmich,Dogariu)实验。通过计算入射光与出射光信号所携带的信息量,发现由于光的波动衍射及光子散粒噪声的影响,出射光所携带的信息量会损失,使得光信号的有效传播速度不会超过真空中的光速。The influence of pulse distortion on superluminal group velocity in an anomalous dispersive medium is researched. The result shows that superluminal group velocity does not disappear even if there is no distortion for light pulse. But the group velocity of a pulse is not equal to the signal velocity. An effective velocity of information transfer is defined based on the information theory, and is applied to explain the experiment that a negative group velocity was observed by Wang, Kuzmich and Dogariu （WKD）. Calculation of the information content of input and output pulse shows that the information content of output pulse will decrease due to diffraction of light wave and noise of photon. The effective velocity of light propagation is not greater than the light velocity in vacuum.

关 键 词：量子光学 光本性的理论 超光速群速度 光信号携带的信息量 信号的有效传播速度 

分 类 号：O431[机械工程—光学工程]