论文标题
纯状态断层扫描和平行未进入的测量
Pure state tomography with parallel unentangled measurements
论文作者
论文摘要
量子状态层析成像（QST）旨在根据对状态副本进行的平均量子测量值估算量子状态。大多数量子算法在某个时候都依赖于QST，这是文献中探索的一个主题，主要用于混合状态。在本文中，我们使用平行的未进入测量值关注纯量子状态的QST。纯状态是所有量子状态的小但有用的子集，它们的断层扫描需要更少的测量，并且本质上是一个相恢复问题。实践中易于实现并行未进入的测量，因为它们允许用户单独测量每个量子。我们提出了两组量子测量值，这些测量值可以在纯状态下进行，以及使用测量结果来识别状态的算法。我们还讨论了如何通过找到最大程度地利用不同可能性变体的测量结果的状态来调整这些估计。提出的三种QST方法的性能通过详细的数值测试验证。
Quantum state tomography (QST) aims at estimating a quantum state from averaged quantum measurements made on copies of the state. Most quantum algorithms rely on QST at some point and it is a well explored topic in the literature, mostly for mixed states. In this paper we focus on the QST of a pure quantum state using parallel unentangled measurements. Pure states are a small but useful subset of all quantum states, their tomography requires fewer measurements and is essentially a phase recovery problem. Parallel unentangled measurements are easy to implement in practice because they allow the user to measure each qubit individually. We propose two sets of quantum measurements that one can make on a pure state as well as the algorithms that use the measurements outcomes in order to identify the state. We also discuss how those estimates can be fined tuned by finding the state that maximizes the likelihood of the measurements with different variants of the likelihood. The performances of the proposed three types of QST methods are validated by means of detailed numerical tests.
