本文应用negativity和concurrence两种纠缠度量标准,考察了双原子与双模光场相互作用系统中,原子间纠缠和光场模间纠缠随时间的演化规律,发现它们在时间演化过程中可以相互转换,在一定条件下两者具有很好的对应关系;对于两量子位系统,negativity和concurrence的取值范围一样,在判断纠缠存在与否的标准上也完全相同,但当系统处于混态时二者的大小不能始终保持一致.
By means of negativity and concurrence, we investigate the time evolution of the entanglement of the two atoms and the entanglement between the two modes in the system of two atoms interacting with two-mode fields. We find the two entanglements can swap with each other, and they have a very good coincidence relation under certain conditions. In two-qubit system, negativity and concurrence in the same range can keep identical with each other on the standard of the existence of entanglement, but they may not always keep pace with each other for mixed states of the system.