Entanglement detection, which signifies the task of distinguishing entangled states from separable states, can be generally performed by realizing entanglement witnesses via local measurements on a single-copy level and classical communication, and are known to be experimenter friendly. We introduce a framework of constructing mirrored entanglement witnesses by showing that an experimental observable is twice as effective since it generally provides bounds from above and below for separable states. Differently stated, a pair of witnesses, mirrored witnesses, exists for the characterization of the bounds, which are two faces of one observable. We show how to generally construct those witnesses and provide examples for bipartite and multipartite systems. We also show that both mirrored witnesses can be improved by introducing nonlinearities, by which a larger set of entangled states can be certified.

纠缠检测表示将纠缠状态与可分离状态区分开来的任务，通常可以通过在单拷贝级别上通过局部测量和经典通信来实现纠缠见证人来执行纠缠检测，并且众所周知，这种方法对实验者友好。通过展示实验可观察者的有效性是我们的两倍，我们介绍了构造镜像纠缠证人的框架，因为它通常为可分离状态提供上下限。换句话说，存在一对证人（镜像的证人）以描绘边界，这是一个可观察到的两个面。我们展示了如何一般地构造那些见证人，并提供了针对两方和多方系统的示例。我们还表明，可以通过引入非线性来改善两个镜像见证人，