For a classical channel, neither the Shannon capacity, nor the sum of conditional probabilities corresponding to the cases of successful transmission can be increased by the use of a non-signaling resource. Yet, perhaps somewhat counterintuitively, entanglement assistance can help and actually elevate the chances of success even in a one-way communicational task that is to be completed by a single-shot use of a noiseless classical channel. To quantify the help that a non-signaling resource provides to a noiseless classical channel, one might ask how many extra letters should be added to the alphabet of the channel in order to perform equally well without the specified non-signaling resource. As was observed by Cubitt, Leung, Matthews, and Winter, there is no upper bound on the number of extra letters required for substituting the assistance of a general non-signaling resource to a noiseless one-bit classical channel. In contrast, here we prove that if this resource is a bipartite quantum system in a maximally entangled state, then an extra classical bit always suffices as a replacement.

翻译：对于古典频道而言,光靠使用非信号资源,光靠香农能力或与成功传输案例相对应的有条件概率之和,都不能增加成功传输案例的附带概率。 然而,也许有些反直觉,纠缠性援助可以帮助和实际提升成功机会,即使在单向通信任务中也是如此,而单向使用无噪音古典频道就能完成这一任务。要量化非信号资源为无噪音古典频道提供的帮助,人们可能会问,在频道的字母表中应添加多少个额外字母,以便在没有指定非信号资源的情况下同样地运行。正如Cubitt、Leung、Matthews和Winter所观察的那样,用普通非信号资源向无噪音的单位古典频道提供协助所需的额外字母数量没有上限。与此形成对照的是,我们在这里证明,如果这一资源是一个极混合的双方量子系统,那么额外的经典部分总是足以替代。