group velocity

基本解释

When the medium density increases (with more atoms), the slow group velocity decreases.
当介质的密度增加时（包含更多的原子），群速度就降低。
In light of this finding, scientists have wondered whether single photons travel at the group velocity or the signal velocity.
在这些发现的基础上，科学家曾经怀疑，是否单个光子可以达到“群速度”和“信号传播速度”。
The main wave packet of a single photon travels no faster than c in any medium, and can be delayed up to 500 ns in a slow light medium where the group velocity is slower than c.
单个光子的波包的传递速度在介质中不比光速快，而且可以在慢光介质中延迟到500纳秒。慢光介质中的群速度比光速慢。

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FORBES: Magazine Article
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FORBES: Magazine Article

the speed at which energy is propagated in a wave. This is the quantity determined when one measures the distance which the radiation travels in a given time. In a medium in which the speed increases with wavelength the group speed is less than the phase speed, and vice versa

群速度
Compared with the case that the defect is non-dispersive, the dispersion of the defect layer leads to an ultraslow group velocity.
与包含无色散缺陷的光子晶体相比，缺陷的色散可导致极慢的群速度。
群速超光速
Theexperimental result reveals that the obvious contrast between the characteristic ofsuperluminal group velocity propagation speed and that of electricity or light in normalpropagation exists.
实验结果揭示了群速超光速传输速度特点与光和电的正常传输情况有明显的区别。
群速
波群速度

群速度
Light with the group velocity faster than the one in a vacuum is defined as fast light.
快光是指在某体系中光的群速度比其在真空中的传播速度要快。
群速