论文标题
及时的真正多零碎纠缠
Genuine Multipartite Entanglement in Time
论文作者
论文摘要
虽然已经对空间量子相关性进行了详细的研究,但对时间过程可以表现出的真正量子相关性知之甚少。使用量子梳形式主义,可以将过程映射到量子状态上,至关重要的差异是时间相关性必须满足因果秩序,而它们的空间对应物则不会以相同的方式限制。在这里,我们利用这种等价性,并使用多方纠缠理论的工具,以全面了解相关结构(因果下降)时间量子过程可以显示。首先,着眼于在两个时间点探测的过程的情况(可以通过三方量子状态等效地描述),我们为在不同分裂中存在两部分纠缠提供了必要的条件。接下来,我们将这些方案连接到先前研究的量子内存,纠缠超级通道和量子转向的概念,从而为时间量子过程中的纠缠提供了物理解释,并确定其创建所需的资源。此外,我们构建了W型和GHz型的明确例子,真正多部分纠缠的两次过程,并证明在时间过程中真正的多部分纠缠可能是一种新现象。最后,我们表明,在任何数量的探测时间内都存在多次跨多次纠缠的过程。
While spatial quantum correlations have been studied in great detail, much less is known about the genuine quantum correlations that can be exhibited by temporal processes. Employing the quantum comb formalism, processes in time can be mapped onto quantum states, with the crucial difference that temporal correlations have to satisfy causal ordering, while their spatial counterpart is not constrained in the same way. Here, we exploit this equivalence and use the tools of multipartite entanglement theory to provide a comprehensive picture of the structure of correlations that (causally ordered) temporal quantum processes can display. First, focusing on the case of a process that is probed at two points in time -- which can equivalently be described by a tripartite quantum state -- we provide necessary as well as sufficient conditions for the presence of bipartite entanglement in different splittings. Next, we connect these scenarios to the previously studied concepts of quantum memory, entanglement breaking superchannels, and quantum steering, thus providing both a physical interpretation for entanglement in temporal quantum processes, and a determination of the resources required for its creation. Additionally, we construct explicit examples of W-type and GHZ-type genuinely multipartite entangled two-time processes and prove that genuine multipartite entanglement in temporal processes can be an emergent phenomenon. Finally, we show that genuinely entangled processes across multiple times exist for any number of probing times.