论文标题
多部分量子相干性的有效估计
Efficient estimation of multipartite quantum coherence
论文作者
论文摘要
连贯性的量化是量子信息处理和基本物理学的核心。相干度量的精确评估通常需要对密度矩阵进行全面重建，这对于大规模多部分系统变得棘手。在这里，我们提出了一种系统的理论方法，可以有效地估计多方状态下连贯性的下限和上限。在稳定剂形式主义下，下限由少量测量值的光谱估计方法确定，并且上限由单个测量确定。我们通过四个Qubit的光学量子系统来验证我们的理论。我们在实验上实施了各种多Qubit的纠缠状态，包括Greenberger-Horne-Horne-Zeilinger状态，群集状态和W状态，并显示如何有效地从几乎没有可观察物的测量中确定它们的相干性。
Quantification of coherence lies at the heart of quantum information processing and fundamental physics. Exact evaluation of coherence measures generally needs a full reconstruction of the density matrix, which becomes intractable for large-scale multipartite systems. Here, we propose a systematic theoretical approach to efficiently estimating lower and upper bounds of coherence in multipartite states. Under the stabilizer formalism, the lower bound is determined by the spectrum estimation method with a small number of measurements and the upper bound is determined by a single measurement. We verify our theory with a four-qubit optical quantum system.We experimentally implement various multi-qubit entangled states, including the Greenberger-Horne-Zeilinger state, the cluster state, and the W state, and show how their coherence are efficiently inferred from measuring few observables.
