Quantum Darwinism builds on decoherence theory to explain the emergence of classical behavior in a fundamentally quantum universe. Within this framework we prove two crucial insights about the emergence of classical phenomenology, centered around quantum discord as the measure of quantumness of correlations. First, we show that the so-called branching structure of the joint state of the system and environment is the only one compatible with zero discord. Second, we prove that for small but nonzero discord and for good but not perfect decoherence, the structure of the globally pure state must be arbitrarily close to the branching form, with each branch exhibiting low entanglement. Our results significantly improve on previous bounds and reinforce the existing evidence that this class of branching states is the only one compatible with the emergence of classical phenomenology, as described by Quantum Darwinism.

中文翻译：

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作为量子宇宙的新兴结构的分支状态


量子达尔文主义建立在退相干理论的基础上，以解释经典行为在基本量子宇宙中的出现。在这个框架内，我们证明了关于古典现象学出现的两个关键见解，以量子不和谐作为相关性量子性的度量为中心。首先，我们表明系统和环境的联合状态的所谓分支结构是唯一与零 discord 兼容的。其次，我们证明，对于小但非零的不和谐和良好但不完美的退相干，全局纯态的结构必须任意接近分支形式，每个分支都表现出低纠缠。我们的结果显着改善了以前的界限，并加强了现有证据，即这类分支状态是唯一与量子达尔文主义所描述的经典现象学的出现相兼容的状态。