非局域性蒸馏

Recent researches showed that, there exists a special kind of nonlocality whose degree of correlation is higher than that of any quantum entangled state. Naturally, one will ask the following questions, what is the intrinsic principle of the nonlocality and it is what that limits the quantum nonlocality from being more stronger. On the other hand,the nonlocality is a powerful physical resource for information processing. The stronger the nonlocal correlation is, the more powerful function it has. So, how to enhance the nonlocality becomes a hot research topic recently. Although, some schemes have been proposed for the distillation of weak nonlocalities, they are only applicable to some specific types of nonlocality, and none of them are universial. So, in this project, we are going to carry out the following studies: 1. By using different combinations of the basic logical operations or the generalized logical operations, we will design an universal distillation scheme for all bipartite binary-input binary-output nonlocally correlated boxes and the distillation scheme for the multipartite and multi-input multi-ouput boxes; 2. By comparing the nonlocality distillation process with the entanglement purification process, we will introduce a probabilistic coupling process and design a probabilistic distillation scheme for nonlocally correlated boxes with a big enhancement of nonlocality; 3. Compare the dynamical process used in nonlocality distillation with that of the entanglement purification, and then study the changing pattern of the entanglement during the nonlocality distillation process and the changing pattern of the nonlocality during the entanglement purificatin process, and thus we can summarize some intrinsic relations between nonlocality and quantum entanglement. Undoubtedly, the above mentioned studies will disclose some physical essence of the nonlocal correlations.

研究表明，存在比量子力学所能达到的非局域关联程度更高的关联，量子非局域性的物理本质以及限制其关联大小的物理机理有待澄清。另外，非局域关联越强，其有用性就越强，故如何提高系统的非局域关联吸引了人们的广泛关注，但目前已有的蒸馏方案仅适用于某些特定类型的非局域关联。针对如何提高系统的非局域关联,本项目拟开展以下研究工作：1、引入逻辑运算的不同组合以及其他广义逻辑运算方式作为非局域性蒸馏方案中的连接方式，设计出更普适的两方两维非局域性蒸馏方案和多方高维非局域性蒸馏方案；2、将非局域性蒸馏和纠缠纯化进行类比，在非局域性蒸馏过程中引入概率耦合，从而设计出以牺牲概率为代价的高效非局域性蒸馏方案；3、比较提高非局域性和纠缠所需的动力学过程，结合对量子非局域性蒸馏过程中的纠缠变化规律和纠缠纯化过程中的非局域性变化规律的研究，揭示出非局域性和纠缠的某些本质联系。同时，上述研究，将有助于揭示非局域性的物理本质。

研究表明，存在比量子力学所能达到的非局域关联程度更高的关联，量子非局域性的物理本质以及限制其关联大小的物理机理有待澄清。另外，非局域关联越强，其有用性就越强，故如何提高系统的非局域关联吸引了人们的广泛关注，但目前已有的蒸馏方案仅适用于某些特定类型的非局域关联。针对如何提高系统的非局域关联，本项目开展了如下研究工作：1、设计提出了一种能够蒸馏两方任意维非局域关联盒子的新的蒸馏方案。该方案不仅能够与现有的两方两维非局域性蒸馏方案兼容，而且能够蒸馏两方高维非局域关联盒子；2、设计提出了同时连接三个盒子的深度为三的自适应性三方两维非局域关联蒸馏方案，并从不同的盒子连接操作的组合方式中筛选出了一种具有很好的蒸馏效果的连接方式组合。结果表明，同时连接三个盒子的(深度为三的)三方非局域关联蒸馏方案比深度为二的蒸馏方案具有更好的蒸馏效果；3、设计提出了一种基于两方两维非局域交换过程的多方两维非局域关联盒子模拟方案，其中的概率耦合过程都只作用于满足自洽性条件的两方两维非局域关联盒子，从而将多个两方两维非局域关联盒子连接为一个多方两维非局域关联盒子，同时克服了多方非局域关联盒子不满足自洽性条件的问题；4、研究了纠缠蒸馏和纠缠交换过程中的量子非局域关联变化规律，结果表明纠缠蒸馏和纠缠交换过程可以将隐藏在初始纠缠态中的非局域关联揭示出来；5、基于Bell检测技术中的非公正探测抽样漏洞设计提出了后量子非局域关联及其蒸馏的物理实现方案。该方案中所利用的器件和技术都是目前光量子信息领域的成熟技术，所以该方案给出了一种实验上且切实可行的研究后量子非局域关联的方法，也为寻找量子非局域关联与后量子非局域关联之间的准确边界提供了研究方法。