中文摘要：

利用零级近似方法讨论了两量子比特Rabi模型中的纠缠动力学问题,分析了不同耦合强度对系统纠缠的影响。这里量子比特和光场的初态分别选取为最大纠缠的Bell态和相干态。通过与数值方法比较,发现当量子比特跃迁频率远小于单模光场的频率时,在超强耦合区域内零级近似方法能够很好地描述系统的纠缠特性。结果显示两量子比特之间的纠缠可呈现突然死亡和产生的现象。而当量子比特之间的纠缠消失时,它们与光场的纠缠可以达到最大值,即两种不同的纠缠相互竞争相互制约。

英文摘要：

We discuss the entanglement dynamics of the two-qubit Rabi model by using the zeroth-order ap- proximation method and analyze the influence of different coupling strength on the entanglement of the system. The two qubits are initially prepared in a maximally entangled state, i.e. Bell state and the field is initially in a coherent state. By comparing the numerical results, we find that the analytical results can well describe the entanglement characteristics of the system in the parameter regime where the qubits transi- tion frequencies are far off-resonance with the field frequency and the interaction strengths reach the ultra- strong coupling regime. The sudden death and generation of entanglement between the qubits are showed in the evolution process of the system. The entanglement between the field and the qubits reaches its maxi- mum when the entanglement between two qubits disappears, which implies that the two kinds of entangle- ments compete with each other.