论文标题
网络非局部性的限制由时间样分离的观察者探测
Limits of network nonlocality probed by time-like separated observers
论文作者
论文摘要
在纠缠交换方案中,如果两个在三方之间共享纠缠状态的消息来源是独立的,那么本地相关性会导致与标准的贝尔不平等(称为网络本地模型)不同的不平等现象。一项高度要求的任务是找到一种方法,使许多玩家在量子网络中非凡地参与其中,因为一般来说,测量结果都会干扰系统。为此,当两个观察者最初共享接近最大纠缠的状态时,我们在这里考虑了一种新型的共享网络非销售方式。我们报告说,通过采用一位观察者进行的UNSHARP测量值,六对可以顺序证明违反双尾相关性的行为,而当两个观察者执行Unsharp测量值时,最多两对观察者都可以表现出双眼。我们还发现,在每个回合中,在UNSHAP测量中涉及的临界噪声,以说明固定共享的纠缠状态作为资源的双范围。我们还建立了共享状态的纠缠含量之间的联系,该连接是通过局部密度矩阵的von-Neumann熵量化的,用于纯状态和werner状态的形成纠缠,以及显示违反胆道相关的最大回合数。通过减少第三方关节测量要素中的纠缠含量,我们观察到,即使在两侧的设置为三个且固定的设置时,即使对于最大纠缠的状态,最大数量也可以减少到两个顺序分享。
In an entanglement swapping scenario, if two sources sharing entangled states between three parties are independent, local correlations lead to a different kind of inequalities than the standard Bell inequalities, known as network local models. A highly demanding task is to find out a way to involve many players nontrivially in a quantum network since measurements, in general, disturb the system. To this end, we consider here a novel way of sharing network nonlocality when two observers initially share close to a maximally entangled states. We report that by employing unsharp measurements performed by one of the observers, six pairs can sequentially demonstrate the violation of bilocal correlations while a maximum of two pairs of observers can exhibit bi-nonlocality when both the observers perform unsharp measurements. We also find the critical noise involved in unsharp measurements in each round to illustrate the bi-nonlocality for a fixed shared entangled state as a resource. We also establish a connection between entanglement content of the shared state, quantified via von-Neumann entropy of the local density matrix for pure states and entanglement of formation for Werner states, and the maximum number of rounds showing violation of bilocal correlations. By reducing entanglement content in the elements of the joint measurement by the third party, we observe that the maximum number reduces to two sequential sharing of bi-nonlocality even for the maximally entangled state when the settings at each side are taken to be three and fixed.