逻辑门操控腔内多光子过程中原子最大相干性恢复  

Logic gate control of maximum coherence restore of atom in multiphoton process

作　　者：罗岸[1] 刘小娟[1] 彭朝晖[1] 刘明伟[1] 贾春霞[1] 姜春蕾[1] 

机构地区：[1]湖南科技大学物理与电子科学学院,湘潭411201

出　　处：《原子与分子物理学报》2016年第2期309-314,共6页Journal of Atomic and Molecular Physics

基　　金：国家自然科学基金(11104068;11405052)

摘　　要：考虑初始处于最大纠缠态的两全同二能级原子,将其中一个注入单模真空态腔场中发生多光子共振相互作用,而将腔外原子及腔场视为腔内原子的环境,研究通过操作腔外原子实现腔内原子最大相干性恢复调控.考察对腔外原子作Hadamard门操作及基态测量前后两种情况下,腔内原子约化密度矩阵非对角元时间演化曲线.结果表明:对腔外原子操作前,腔内原子总是处于混合态或经典态,相干性不能恢复;对腔外原子操作后,腔内原子密度矩阵非对角元呈现周期性演化,最大相干性可周期性恢复,而且最大相干性恢复周期随光子数目k增大而变小.通过利用腔场与原子之间的共振相互作用和原子之间的纠缠,可实现腔内原子相干性恢复远程控制,与单光之过程相比,多光子过程更有利于原子相干性的恢复.Considering two identical two- level atoms initially in maximally entangled state, we inject one atom into a single -mode vacuum cavity to produce muhiphoton resonance while the other is outside the cavity. The cavity field and atom outside the cavity are seen as the environment, and we investigate the control of atomic maximum coherence restore in the cavity. We study the time evolution curve of the off - diagonal elements of the reduced density matrix for the atom inside the cavity for two cases, i. e. , before and after performing Hadamard gate operation and the ground state measurement on the atom outside the cavity. The results show that, before operations on the atom outside the cavity, the atom inside the cavity is always in a mixed state or classical state, and its coherence is always suppressed. However, after operations on the atom outside the cavity, the off - diago- nal elements in the reduced density matrix of the atom inside the cavity evolve periodically, and the maximum co- herence of the atom inside the cavity can recover periodically. Furthermore, the period of maximum coherence recovery become short with the increase of photon number k. So that, it is realizable to control the coherence restoration for the atom inside the cavity by means of the resonance between atoms and the cavity, and entangle- ment of atoms. Comparing with the single - photon process, muhiphoton process may be more advantageous to restore atomic coherence.

关 键 词：逻辑门操作 基态测量 多光子过程 原子最大相干性恢复 

分 类 号：O56[理学—原子与分子物理]