signal velocity

基本解释

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 scientists found that the precursor wave front of a single photon always travels at c, like the signal velocity of large groups of photons.
科学家发现，单个光子的前驱波头一般以光速c传播，就像由大量光子携带的信号的传播速度一样。
Although previous studies have found that the "group velocity" of light can travel faster than c, the "signal velocity" –the speed at which information travels –cannot.
尽管先前的研究已经证实，光的“群速度”可以超越光速c，而“信号传播速度”——光携带的信息的传播速度——不能超越光速。

In this case, the signal is a particle's momentum—that is its mass times its velocity.
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