We introduce a graphical language for coherent control of general quantum channels inspired by practical quantum optical setups involving polarising beam splitters (PBS). As standard completely positive trace preserving maps are known not to be appropriate to represent coherently controlled quantum channels, we propose to instead use purified channels, an extension of Stinespring's dilation. We characterise the observational equivalence of purified channels in various coherent-control contexts, paving the way towards a faithful representation of quantum channels under coherent control.
翻译:我们引入了一种图形语言,用于在包括波束分解器(PBS)的实用量子光学装置的启发下,对普通量子信道进行一致控制。 由于标准的完全正面的跟踪保存地图被认为不适合代表一致控制的量子频道,我们建议使用纯化的渠道,即Stinespring的扩展。 我们描述在各种一致控制环境下纯化的渠道的观测等同性,为在一致控制下忠实代表量子频道铺平了道路。