失谐对冷原子介质中光脉冲信息存储的影响

Effects of detuning on the storage of a light pulse in an ultracold atomic medium

通过对电磁感应透明模型的理论推导和数值模拟 ,讨论了光场和原子能级间有失谐的光脉冲信息的存储过程 .结果表明 :只有在光场和原子能级共振时 ,光和原子相互作用系统的存储态才能最终演化到暗态 .随着失谐量的增大 ,只有部分信号光脉冲存储于冷原子介质中 ,并且光脉冲负群速度的绝对值逐渐增大 ,导致在介质中“读出”信号光相对于“读入”信号光的位置有明显的倒退现象 .对于能级上下对称相同失谐的情况 ,存储过程中系统各物理量的演化过程几乎相同 .

Theoretical analysis and a full numerical simulation of the electromagnetically induced transparency model are performed under detuning conditions for a closed three-level ultracold atomic system in which a signal field can be stored and retrieved. Numerical results confirm the theory that the system can be prepared in dark states only under resonant conditions between the fields and the atomic transitions. The signal field is partially stored in the ultracold atomic medium with the increase of detuning and an enhanced negative group velocity of the physically vanishing signal pulse appears. In the case of a symmetrical detuning (red or blue detuning),no remarkable changes of the storage process occur.