We present a family of easily computable upper bounds for the Holevo (information) quantity of an ensemble of quantum states depending on a reference state (as a free parameter). These upper bounds are obtained by combining probabilistic and metric characteristics of the ensemble. We show that an appropriate choice of the reference state gives tight upper bounds for the Holevo quantity which in many cases improve the estimates existing in the literature. We also present an upper bound for the Holevo quantity of a generalized ensemble of quantum states with finite average energy depending on the metric divergence of an ensemble. In the case of a multi-mode quantum oscillator, this upper bound is tight for large energy. Upper bounds for the Holevo capacity of finite-dimensional quantum channels depending on metric characteristics of the channel output are obtained.

中文翻译：

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Holevo信息量的上限及其使用

我们给出了一组量子态的霍夫（信息）量的容易计算的上限，量子量取决于参考态（作为自由参数）。这些上限是通过组合整体的概率和度量特征获得的。我们证明了参考状态的一个合适的选择给出了在许多情况下提高现有文献的估计Holevo量紧张的上限。我们还给出了具有有限平均能量的广义量子态整体的Holevo量的上限，具体取决于整体的度量散度。在多模量子振荡器的情况下，该上限对于大能量而言是紧密的。