基于量子相干控制吸收的准Λ型四能级原子局域化研究

Study on atomic localization of Λ-type quasi-four level atoms based on absorption with quantum coherent control

提出了一种基于量子相干控制吸收的对准Λ型四能级原子进行二维局域化方案.利用密度矩阵微扰理论,得到了确定原子空间位置信息的筛选函数解析表达式.在缀饰态表象中,分析了在相干控制场作用下原子初始状态对原子局域的影响.数值模拟了控制场参量对原子局域化结果的影响.研究发现原子局域化结果与初始时刻在控制场作用下原子在下能态的布局、下能级间产生的极化密切相关;不管探测场与耦合场是否满足电磁感应透明配置条件,通过改变控制场中的行波场的振幅和探测场的失谐量,均可实现高精度原子局域化,在亚波长范围内测量到原子的概率达到100%.

A scheme of two-dimensional atomic localization of theΛ-type quasi-four-level atoms based on quantum-coherent-controlled absorption is proposed. Using the perturbation theory of the density matrix, the filter function is derived for the position probability distribution of atoms, which is determined by the imaginary part of the optical susceptibility. Because of the space-dependent interaction between atoms and fields, the position information is contained in the filter function, which provides an approach to explore the spacial position probability distribution of a single atom. Effect of the initial state of the atom under coherent control on the atomic localization is analyzed. It is found that the atomic localization is related to the initial atom distribution and the dipole moment between two lower levels under the coherent field control. When probing field and coupling field are under the configuration of the electromagnetically induced transparency, the position of atoms can be localized in the domain of sub wavelength; when the electromagnetically induced transparency is not satisfied, an atom can be measured in a sub wave region with the probability of 100% by changing the traveling wave amplitude in the controlling field and the detuning in the probing field.