论文标题
因果结构的量子叠加,作为非本地量子操作的局部实施的通用资源
Quantum superposition of causal structures as a universal resource for local implementation of nonlocal quantum operations
论文作者
论文摘要
空间分离限制了在分布式多部分量子系统上局部可实施的量子操作集。我们建议,由于不同时空几何形状的量子叠加而引起的无限性因果结构可以用作独立的通用资源,用于在空间分布的量子系统上局部实施任何量子操作。因此,所有这些量子任务无法通过本地操作和经典交流(LOCC)来完成的所有这些量子任务,也只能在本地实现。我们表明,将无限期的因果结构作为唯一资源,可以将一个代理子系统的状态完美地传送到另一个遥远的实验室,以至于遥远的实验室的代理可以在其或她的实验室中访问整个最初共享状态并可以在本地进行联合国家进行任何全球量子操作。我们进一步发现,在传送过程之后,资源 - 时空的无限因果结构不会被消耗。因此,在实施所需的量子操作后,可以使用相同的资源将第一代理子系统的状态传送回其先前的实验室。我们表明,对于本地执行所有仅通过LOCC无法实现的非本地量子任务而言,这种双向传送并不总是必要的。在不调用任何类型的传送的情况下,我们提出了一项协议,用于对四个铃铛状态的完美局部歧视,这些钟声将无限期的因果结构视为唯一的资源。作为即时的展示,我们提供了更多的非本地任务示例,例如对表现出``量子非定位性''而不构成的量子歧视的局部歧视,以及激活有限的纠缠状态的激活,这些状态也可以通过我们提议的协议可以实现的协议来实现,这些协议将不确定的因果关系结构纳入资源。
Spatial separation restricts the set of locally implementable quantum operations on distributed multipartite quantum systems. We propose that indefinite causal structure arising due to quantum superposition of different space-time geometries can be used as an independent universal resource for local implementation of any quantum operation on spatially distributed quantum systems. Consequently, all such quantum tasks that are not accomplishable by local operations and classical communication (LOCC) only also become locally accomplishable. We show that exploiting indefinite causal structure as the sole resource, it is possible to perfectly teleport the state of one agent's subsystem to the other distant laboratory in such a way that the agent at the distant laboratory can have access to the whole initially shared state in his or her laboratory and can perform any global quantum operation on the joint state locally. We further find that, after the teleportation process, the resource -- indefinite causal structure of the space-time does not get consumed. Hence, after implementing the desired quantum operation the state of the first agent's subsystem can be teleported back to its previous laboratory using the same resource. We show that this two-way teleportation is not always necessary for locally executing all nonlocal quantum tasks that are not realisable by LOCC only. Without invoking any kind of teleportation, we present a protocol for perfect local discrimination of the set of four Bell states that exploits indefinite causal structure as the sole resource. As immediate upshots, we present some more examples of such nonlocal tasks as local discrimination of the set of states exhibiting ``quantum nonlocality without entanglement" and activation of bound entangled states that are also achievable by our proposed protocol incorporating indefinite causal structure as a resource.