标题： 熵扰的下半连续性及其在量子信息论中的应用 显示英文标题

标题： Lower semicontinuity of the entropic disturbance and its applications in quantum information theory

摘要： 我们证明了对于任意无限维量子信道，熵扰动（定义为广义系综的 $\chi$-量与其在信道作用下图像的该量之差）在其自然定义集上是下半连续的。 我们还得到了这一性质的一些有用的推论，特别是我们证明了在能量型输入约束下，任何量子信道的输出 $\chi\textrm{-}$量是连续的，并且存在 $\chi$-最优系综。 显示英文摘要

摘要： We prove that for any infinite-dimensional quantum channel the entropic disturbance (defined as difference between the $\chi$-quantity of a generalized ensemble and that of the image of the ensemble under the channel) is lower semicontinuous on the natural set of its definition. We establish a number of useful corollaries of this property, in particular, we prove the continuity of the output $\chi\textrm{-}$quantity and the existence of $\chi$-optimal ensemble for any quantum channel under the energy-type input constraint.