Sawerwain Marek, Wiśniewska Joanna, Gielerak Roman
Institute of Control & Computation Engineering, University of Zielona Góra, Licealna 9, 65-417 Zielona Góra, Poland.
Institute of Information Systems, Faculty of Cybernetics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Poland.
Entropy (Basel). 2021 Jun 4;23(6):717. doi: 10.3390/e23060717.
Information switching and swapping seem to be fundamental elements of quantum communication protocols. Another crucial issue is the presence of entanglement and its level in inspected quantum systems. In this article, a formal definition of the operation of the swapping local quantum information and its existence proof, together with some elementary properties analysed through the prism of the concept of the entropy, are presented. As an example of the local information swapping usage, we demonstrate a certain realisation of the quantum switch. Entanglement levels, during the work of the switch, are calculated with the Negativity measure and a separability criterion based on the von Neumann entropy, spectral decomposition and Schmidt decomposition. Results of numerical experiments, during which the entanglement levels are estimated for systems under consideration with and without distortions, are presented. The noise is generated by the Dzyaloshinskii-Moriya interaction and the intrinsic decoherence is modelled by the Milburn equation. This work contains a switch realisation in a circuit form-built out of elementary quantum gates, and a scheme of the circuit which estimates levels of entanglement during the switch's operating.
信息交换似乎是量子通信协议的基本要素。另一个关键问题是被检测量子系统中纠缠的存在及其程度。本文给出了局部量子信息交换操作的形式化定义及其存在性证明，并通过熵的概念分析了一些基本性质。作为局部信息交换应用的一个例子，我们展示了量子开关的一种实现方式。在开关工作过程中，利用负性度量以及基于冯·诺依曼熵、谱分解和施密特分解的可分性判据来计算纠缠程度。给出了数值实验结果，在此实验中对有失真和无失真情况下所考虑系统的纠缠程度进行了估计。噪声由Dzyaloshinskii - Moriya相互作用产生，固有退相干由米尔本方程建模。这项工作包含了一种由基本量子门构建的电路形式的开关实现方式，以及一种在开关操作过程中估计纠缠程度的电路方案。
