Quantum networks lead to novel notions of locality and correlations and an important problem concerns the question of which quantum states can be experimentally prepared with a given network structure and devices and which not. We prove that all multi-qubit graph states arising from a connected graph cannot originate from any quantum network with bipartite sources, as long as feed-forward and quantum memories are not available. Moreover, the fidelity of a multi-qubit graph state and any network state cannot exceed 9/10. Similar results can also be established for a large class of multi-qudit graph states.

中文翻译：

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量子LOSR网络无法生成高保真度的图状态

量子网络带来了局域性和相关性的新概念，一个重要的问题涉及哪些量子态可以用给定的网络结构和设备通过实验制备，哪些不能。我们证明，只要前馈和量子存储器不可用，由连通图产生的所有多量子位图状态就不能源自任何具有二分源的量子网络。此外，多量子位图状态和任何网络状态的保真度不能超过 9/10。对于一大类多qudit图状态也可以建立类似的结果。