We consider the entanglement evolution of two qubits embedded into disordered multiconnected environment. We model the environment and its interaction with qubits by large random matrices allowing for a possibility to describe environments of meso- and even nanosize. We obtain general formulas for the time dependent reduced density matrix of the qubits corresponding to several cases of the qubit-environment interaction and initial condition. We then work out an analog of the Born–Markov approximation to find the evolution of the widely used entanglement quantifiers: the concurrence, the negativity and the quantum discord. We show that even in this approximation the time evolution of the reduced density matrix can be non-Markovian, thereby describing certain memory effects due to the backaction of the environment on qubits. In particular, we find the vanishing of the entanglement (Entanglement Sudden Death) at finite moments and its revivals (Entanglement Sudden Birth). Our results, partly known and partly new, can be viewed as a manifestation of the universality of certain properties of decoherent qubit evolution which have been found previously in various versions of bosonic macroscopic environment.

中文翻译：

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共同环境中两个量子比特的动力学

我们考虑嵌入到无序多连接环境中的两个量子比特的纠缠演化。我们通过大型随机矩阵对环境及其与量子比特的相互作用进行建模，从而有可能描述介观甚至纳米级的环境。我们获得了与量子位-环境相互作用和初始条件的几种情况相对应的量子位的时间相关降低密度矩阵的通用公式。然后，我们计算出 Born-Markov 近似的类似物，以找到广泛使用的纠缠量词的演变：同时性、负性和量子不和谐。我们表明，即使在这种近似中，降低密度矩阵的时间演化也可能是非马尔可夫的，从而描述了由于环境对量子比特的反作用而导致的某些记忆效应。特别是，我们发现纠缠在有限的时刻消失（纠缠猝死）和它的复兴（纠缠猝生）。我们的结果，部分是已知的，部分是新的，可以看作是之前在各种版本的玻色子宏观环境中发现的去相干量子比特演化的某些特性的普遍性的体现。