近日，印度Harish-Chandra研究所的Ujjwal Sen及其研究团队取得一项新进展。经过不懈努力，他们实现了局部噪声信道中纠缠的保存。相关研究成果已于2024年8月13日在国际知名学术期刊《物理评论A》上发表。
该研究团队考虑了局部噪声对共享量子态的影响，并评估了可以免受劣化影响的纠缠量。保存的纠缠量不仅取决于信道的强度，还取决于信道的类型，尤其是，对于去极化信道，保存的纠缠量总是为零。本工作的主要动机是通过研究相应信道的特性来分析保存的纠缠量产生这种依赖性的原因。
在此背景下，研究人员量化了信道对不同作用态的偏向性，并对其进行了探究。研究人员假定，对于去极化信道和幺正信道，所有偏向性度量都必须为零，并随后引入了几种偏向性度量。研究人员还考虑了信道的纠缠容量。
研究人员观察到，偏向性量化指标和纠缠容量的联合行为解释了保存的纠缠量的性质。此外，他们发现了一对保存纠缠量的上界，它们似乎模仿了后者的图形性质。
据悉，受噪声影响的纠缠无法避免衰减。但是，在许多噪声信道的情况下，可以使用局部幺正操作来部分防止纠缠退相干。
附：英文原文
Title: Preservation of entanglement in local noisy channels
Author: Priya Ghosh, Kornikar Sen, Ujjwal Sen
Issue&Volume: 2024/08/13
Abstract: Entanglement subject to noise cannot be shielded against decaying. But, in case of many noisy channels, the degradation can be partially prevented by using local unitary operations. We consider the effect of local noise on shared quantum states and evaluate the amount of entanglement that can be preserved from deterioration. The amount of saved entanglement not only depends on the strength of the channel but also on the type of the channel, and in particular, it always vanishes for the depolarizing channel. The main motive of this work is to analyze the reason behind this dependency of saved entanglement by inspecting properties of the corresponding channels. In this context, we quantify and explore the biasnesses of channels towards the different states on which they act. We postulate that all biasness measures must vanish for depolarizing and unitary channels, and subsequently introduce a few measures of biasness. We also consider the entanglement capacities of channels. We observe that the joint behavior of the biasness quantifiers and the entanglement capacity explains the nature of saved entanglement. Furthermore, we find a pair of upper bounds on saved entanglement which are noticed to imitate the graphical nature of the latter.
DOI: 10.1103/PhysRevA.110.022419
Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.022419
来源：科学网 小柯机器人