电磁诱导下Y型四能级原子系统的左手效应

Electromagnetically Induced Left Handedness in Y-type Four Level Atomic System

采用了一个闭合的Y型四能级原子系统,在多模光场的作用下,利用量子相干技术使其实现介质的左手效应,使介质具备左手材料特性.在相互作用表象下,考虑偶极近似和旋转波近似利用密度矩阵方程并结合相关条件下的有关公式进行理论计算.数值模拟结果显示:在合适的参量条件下,介质的相对介电常量和相对磁导率可以同时出现负值,产生了左手效应,相应的介质转化为左手材料.在弱探测场条件下,当探测光的拉比频率增加时,介质实现左手效应的频率范围减小并且与之相对应的折射率和吸收系数也发生变化.通过讨论在左手效应成立的条件下介质对光场的吸收和增益问题,结果表明:在弱探测场条件下,利用电磁诱导的方法也可以实现介质的左手效应,使得左手材料在实验上的实现也得到了进一步的扩展,同时也扩展了电磁诱导的应用领域.

The quantum system with an interaction between a closed Y-type four-level atom and multi-mode light fields is adopted to possess left handedness by means of the technique of quantum coherence. In the representation of interaction, the density matrix method is utilized in view of the rotating-wave approximation and the di-pole approximation.The conclusion of the numerical simulation shows that under the appropriate parameter conditions, the medium can achieve negative permittivity and negative permeability simultaneously （i.e. the left handedness effect happens and the left-handed material is realized.） In the condition of the weak probe field, when the Rabi frequency of probe light increases, the frequency range of the medium to achieve its left-handed effect decreases and the refractive index and absorption coefficient will also changed correspondingly. The medium to affect light absorption and gain in the conditions of the establishment of left -handed effect are also discussed. The paper can be concluded that, in the conditions of weak probe field, the electro-magnetic induction can be used to achieve the left-handed effect of the medium, which extends the implementation of left-handed materials in the experiment, and extends the application field of electro-magnetic induction.