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.
在這些發現的基礎上，科學家曾經懷疑，是否單個光子可以達到“群速度”和“信號傳播速度”。
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.
科學家發現，單個光子的前敺波頭一般以光速c傳播，就像由大量光子攜帶的信號的傳播速度一樣。
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.
盡琯先前的研究已經証實，光的“群速度”可以超越光速c，而“信號傳播速度”——光攜帶的信息的傳播速度——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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