论文标题
贸易因果秩序
Trading causal order for locality
论文作者
论文摘要
量子理论接纳了量子非局部性的合奏，而无需纠缠（QNLWE）。这些合奏由看似古典的状态（它们是完全可区分的和非输入的）组成的，这些状态不能完全歧视本地操作和经典交流（LOCC）。在这里，我们从因果的角度分析了Qnlwe，并展示了如何使用本地操作和经典交流而没有确定的因果关系来完美地歧视其中一些集团。具体来说，三方访问了无限期因果秩序实例 - AF/BW Process-Can在Qnlwe合奏中完美区分了状态 - 移动合奏 - 与本地操作。因此，这种类型的量子非局部性以牺牲确定的因果秩序而消失，同时保留经典的交流。我们的结果从而利用了LOCC是三个约束的结合的事实：本地操作，经典交流和确定的因果秩序。此外，我们展示了如何将AF/BW工艺的多部分概括转换为展示QNLWE的多QUIPIT集合。此类合奏对于加密协议和研究LOCC无法实现的可分离量子操作具有独立的兴趣。
Quantum theory admits ensembles of quantum nonlocality without entanglement (QNLWE). These ensembles consist of seemingly classical states (they are perfectly distinguishable and non-entangled) that cannot be perfectly discriminated with local operations and classical communication (LOCC). Here, we analyze QNLWE from a causal perspective, and show how to perfectly discriminate some of these ensembles using local operations and classical communication without definite causal order. Specifically, three parties with access to an instance of indefinite causal order-the AF/BW process-can perfectly discriminate the states in a QNLWE ensemble--the SHIFT ensemble--with local operations. Hence, this type of quantum nonlocality disappears at the expense of definite causal order while retaining classical communication. Our results thereby leverage the fact that LOCC is a conjunction of three constraints: local operations, classical communication, and definite causal order. Moreover, we show how multipartite generalizations of the AF/BW process are transformed into multiqubit ensembles that exhibit QNLWE. Such ensembles are of independent interest for cryptographic protocols and for the study of separable quantum operations unachievable with LOCC.
