由任意多个独立的观察者共享Werner态的纠缠  

Sharing entanglement of the Werner state by arbitrarily many independent observers

作　　者：于欣淼 杨舒媛 贺衎 Yu Xin-Miao;Yang Shu-Yuan;He Kan(Department of Mathematics,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学数学学院,太原030024

出　　处：《物理学报》2023年第7期2-8,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12271394);山西省重点研发计划(批准号:202102010101004)资助的课题.

摘　　要：量子关联共享问题是量子信息理论研究中一个有趣的课题.最近,Srivastava等在[Phys.Rev.A 2022105062413]中证明了存在一类T态,其纠缠可以被任意多个独立观察者共享.通过选择合适的纠缠见证算子和Bob的非锐化测量,本文证明了存在两量子比特纠缠的初始共享Werner态,其纠缠可以被任意多个观察者Bobs和单个观察者Alice共享.The problem of sharing quantum correlations is an interesting problem in the study of quantum information theory.Silva et al.proposed the study of sharing quantum nonlocality at first.They studied the fundamental limits on nonlocality,asking whether a single pair of entangled qubits could generate a long sequence of nonlocal correlations.At the same time,the sequential scenario was also introduced first,in which Alice and Bob each have half of a pair of entangled qubit states.The first Bob measures his half and then passes his part to a second Bob who measures again and so on.Obviously,even partial preservation of entanglement in a shared state in spite of a few sequences of local operations performed by the sharing parties can be important for information processing schemes in which entanglement is utilized as a resource.Thus,the problem of sharing quantum entanglement has also been extensively investigated.Recently,Srivastava et al.proved that there exist a class of T-states whose entanglement can be shared by arbitrarily many independent observers in[Phys.Rev.A 2022105062413].Here,we want to find whether there are other entangled states that can be shared entanglement arbitrarily many times.In this paper,we consider the problem of sharing quantum entanglement when the initial shared state is a two-qubit entangled Werner state.The goal is to maximize the number of Bobs that can share entanglement with a single Alice.By suitably choosing the entanglement witness operator and the unsharp measurement settings by the Bobs,we prove that there exist two-qubit entangled initial shared Werner states whose entanglement can be detected by arbitrarily many sequential observers Bobs with a single Alice.Then,we also consider the special case of the Werner state,that is,the maximally entangled state as the initial shared state.In this case,its entanglement can also be witnessed arbitrarily many times,and the number of Bobs increases with the decrease of parameter.

关 键 词：纠缠 WITNESS Werner 态 共享量子纠缠 

分 类 号：O413[理学—理论物理]