与原子依赖强度耦合双模压缩真空态的量子纠缠

Entanglement of two-mode squeezing vacuum state field interacting with atom via intensity-dependent coupling

在考虑原子与双模光场依赖强度耦合双光子共振相互作用的条件下,应用量子相对熵研究了双模压缩真空场模间纠缠度的演化.结果表明,在原子与光场相互作用之后,模间纠缠度作周期性的变化.在强场条件下,模间纠缠度总是在初始时刻达到最大值,其变化幅度基本保持不变.在初始场很弱的条件下,纠缠度演化的特点与原子初始状态有关,当原子处于激发态和基态的等概率叠加态时,纠缠度变化的幅度最大.控制原子与光场的作用时间及原子的初态,可以调整双模光场间的纠缠.

Under the condition of two-mode squeezed vacuum state field interacting with an atom via the intensity-dependent coupling,the degree of entanglement between the two mode fields is investigated by using quantum relative entropy.It is found that the evolution of degree of two-mode fields entanglement is periodic.When the initial field is strong,the degree of entanglement reach maximum at scaled time gt=kπ(k=0,1,2,…),and the different between the maximum and minimum of the entanglement measures is about 1.3 generally.When the initial field is very weak,the influence of atom initial state on the entanglement evolution is sensitive.And the maximum entanglement appears under the situation of atom in a superposition state of upper level and lower level with equal probability.The entanglement of the two mode fields can be adjusted by controlling the time of the atom passing the cavity and the initial state of the atom.