Simple procedure for phase-space measurement and entanglement validation
Simple procedure for phase-space measurement and entanglement validation
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DOI：
10.1103/physreva.96.022117
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发表时间：
2017-08-10
影响因子：
2.9
通讯作者：
Everitt, M. J.
中科院分区：
文献类型：
--
作者：
Rundle, R. P.;Mills, P. W.;Everitt, M. J.
最近有研究表明，可以用相空间准概率分布（Wigner函数）来表示任何系统的完整量子态[物理学]。生态学报，2017,18(6)。这样的函数采用可观测值的期望值的形式，它与位移奇偶运算符有直接的类比。在这项工作中，我们给出了一个测量维格纳函数的程序，它应该适用于任何量子系统。我们已经将我们的程序应用于IBM的量子体验五量子位量子处理器，以证明我们可以测量和生成两种不同贝尔状态的维格纳函数以及五量子位格林伯格-霍恩-塞林格状态。由于自旋系统的Wigner函数不是唯一的，我们定义、比较和对比了两个不同的例子。我们展示了这些维格纳函数的使用如何导致量子态分析的最佳方法，特别是在特定特征特征特别感兴趣的情况下（例如自旋薛定谔猫态）。此外，我们表明，这种分析导致了直接的，并且可能非常有效的纠缠测试和状态表征方法。
It has recently been shown that it is possible to represent the complete quantum state of any system as a phase-space quasiprobability distribution (Wigner function) [Phys. Rev. Lett. 117, 180401 (2016)]. Such functions take the form of expectation values of an observable that has a direct analogy to displaced parity operators. In this work we give a procedure for the measurement of the Wigner function that should be applicable to any quantum system. We have applied our procedure to IBM's Quantum Experience five-qubit quantum processor to demonstrate that we can measure and generate the Wigner functions of two different Bell states as well as the five-qubit Greenberger-Horne-Zeilinger state. Because Wigner functions for spin systems are not unique, we define, compare, and contrast two distinct examples. We show how the use of these Wigner functions leads to an optimal method for quantum state analysis especially in the situation where specific characteristic features are of particular interest (such as for spin Schrodinger cat states). Furthermore we show that this analysis leads to straightforward, and potentially very efficient, entanglement test and state characterization methods.