By means of collision models (CMs) where the environment is simulated by a collection of ancillas consisting of two entangled qubits, we investigate the effects of entanglement in the environment on the non-Markovianity of an open quantum system. Two CMs are considered in this study, in the first one the open quantum system S directly collides with the environment, while in the second one the system interacts with two intermediate qubits which, in turn, are coupled to the environment. We show that it is possible to enhance the non-Markovianity by environment entanglement in both models. In particular, in the second model, we show that the initial state of the auxiliary qubits can also affect the non-Markovianity of the system and there exists the optimal combination of the initial environmental state and the initial state of auxiliary qubits. In this case, the non-Markovianity can be greatly enhanced.

By means of collision models (CMs) where the environment is simulated by a collection of ancillas consisting of two entangled qubits, we investigate the effects of entanglement in the environment on the non-Markovianity of an open quantum system. Two CMs are considered in this study, in the first one the open quantum system S直接与环境碰撞，而在第二个中，系统与两个中间量子比特相互作用，而后者又与环境耦合。我们表明，可以通过两种模型中的环境纠缠来增强非马尔可夫性。特别是，在第二个模型中，我们证明了辅助量子位的初始状态也会影响系统的非马尔可夫性，并且存在初始环境状态和辅助量子位初始状态的最佳组合。在这种情况下，可以大大增强非马尔可夫性。