The dynamical behaviors of the entanglement for the excitons in a system of two coupled quantum dots and a single-mode cavity field are investigated for two different initial conditions by means of the concurrence. It is shown that the direct coupling between the dots can reduce the degree of the entanglement for the excitons. For the initial cavity field being in the odd-coherent state, the degree of their entanglement decreases with the increase of the coherent intensity of cavity field. There is a trade-off for excitonic entanglement when cavity field is initially prepared in the even-coherent state. The relation between the average photon numbers of cavity field and quasi-maximally entangled excitonic coherent states is studied.%利用共生纠缠度研究了单模腔场内两个耦合量子点中激子的纠缠动力学行为.结果表明:无论腔场初始制备于奇相干态还是偶相干态,两个量子点间直接耦合作用均能减弱激子的纠缠度.在腔场初始为奇相干态时,激子的纠缠度随场模强度的增加而减小;偶相干态时,激子的纠缠度呈现一个转折变化.此外,也研究了单模腔场内平均光子数与激子准最大相干纠缠态的关联.
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