论文标题
通过忠诚见证对纠缠状态的无损验证
Nondestructive Verification of Entangled States via Fidelity Witnessing
论文作者
论文摘要
评估嘈杂纠缠状态的合奏的质量是量子信息处理的核心任务。通常，这是通过测量并破坏多个副本来完成的，可以利用国家断层扫描或忠诚度估算来表征状态。在这里，我们提出了几种直接区分两种不同状态的方法，例如如果它们的保真度高于或低于一定阈值。事实证明，这要高得多，并且重要的是使经过验证的状态保持完整。我们利用辅助纠缠或更大尺寸的合奏，在整个合奏中运行，但仅在集中信息的情况下测量一小部分。对于某些国家家庭，我们证明了这种方法甚至可以超过最佳方法，这些方法共同衡量了合奏的固定部分。
Assessing the quality of an ensemble of noisy entangled states is a central task in quantum information processing. Usually this is done by measuring and hence destroying multiple copies, from which state tomography or fidelity estimation can be employed to characterize states. Here we propose several methods to directly distinguish between two different sets of states, e.g. if their fidelity is above or below a certain threshold value. This turns out to be significantly more efficient, and importantly keeps the verified states intact. We make use of auxiliary entanglement or an ensemble of larger size, where we operate on the whole ensemble, but measure only a small fraction where information has been concentrated. For certain state families, we demonstrate that such an approach can even outperform optimal methods that collectively measure directly a fixed fraction of the ensemble.
