论文标题
量学上有用的真实多部分纠缠的激活
Activation of metrologically useful genuine multipartite entanglement
论文作者
论文摘要
我们考虑使用几个副本和多部分量子状态的量子计量学。我们通过确定国家的表现要优于可分离状态来表征计量学的实用性。我们确定了一大批纠缠状态，这些状态在大量副本限制下对计量学上具有最大有用的状态，即使国家纠缠较弱，甚至比可分离状态更有用。这样，我们激活了在阶段上有用的真实多部分纠缠。值得注意的是，不仅在副本数量中，最大可实现的计量学实用性是指数迅速达到的，而且可以通过测量很少的简单相关性可观察物来实现。我们还对纯纠缠状态的单个副本的有用性做出了一般性陈述。我们出人意料地发现，Hyllus等人呈现的多Quipit状态。 [物理。 Rev. A 82，012337（2010）]，如果我们将Qutrits局部嵌入Qutrits，则无用。我们讨论了我们方案与误差校正的关系，以及在嘈杂的环境中可能使用量子计量学的可能性。
We consider quantum metrology with several copies of bipartite and multipartite quantum states. We characterize the metrological usefulness by determining how much the state outperforms separable states. We identify a large class of entangled states that become maximally useful for metrology in the limit of large number of copies, even if the state is weakly entangled and not even more useful than separable states. This way we activate metrologically useful genuine multipartite entanglement. Remarkably, not only that the maximally achievable metrological usefulness is attained exponentially fast in the number of copies, but it can be achieved by the measurement of few simple correlation observables. We also make general statements about the usefulness of a single copy of pure entangled states. We surprisingly find that the multiqubit states presented in Hyllus et al. [Phys. Rev. A 82, 012337 (2010)], which are not useful, become useful if we embed the qubits locally in qutrits. We discuss the relation of our scheme to error correction, and its possible use for quantum metrology in a noisy environment.
