超冷里德堡原子的外场操控

发布时间：2018-03-18 12:06

本文选题：超冷里德堡原子　切入点：极性里德堡原子气体　出处：《山西大学》2016年博士论文　论文类型：学位论文

【摘要】：里德堡原子是外层电子被激发到主量子数很大n1)的激发态原子,具有相互作用强(～n4)、辐射寿命长(～n3)、极化率大(～n7)等奇特性质,因而一直受到人们的广泛关注。超冷里德堡原子之间由于强的偶极-偶极相互作用产生的偶极阻塞效应,使里德堡原子成为实现可控量子逻辑门、量子信息处理、单光子源及多体物理等研究的理想备选介质,在近年来成为研究的热点。本文以铯原子为介质,利用激光冷却和俘获技术在磁光阱中制备了温度为-100μK、密度为～109cm-3的超冷原子团。利用双光子激发的方式制备了超冷里德堡原子,利用脉冲场电离法探测里德堡原子电离后的离子谱。通过原子团两侧的栅极板施加外部电场实现对超冷里德堡原子的操控。由于nS里德堡态具有很小的分数量子亏损,其能级接近于(n-4)类氢多重态,因此在很小的电场中会与之形成态混合以及能级的回避交叉。本文通过对外场中里德堡原子斯塔克谱的精密测量,详细研究了nS态与(n-4)类氢态的回避交叉。并在此基础上利用实验测量的回避交叉与理论模拟相对比,提出了一种修正nS态量子亏损的新方法；此外,通过绝热地操控外场使初始制备的nS态原子布居到高-l里德堡斯塔克态,制备了一种高极性的里德堡原子气；最后,通过精密调控电场两次通过同一回避交叉,制备了一种新型里德堡原子干涉仪。具体如下：一.在磁光阱中通过双光子激发在外场中精密测量了49S1/2态和n=45高-l多重态形成的三能级回避交叉离子谱。通过量子模拟比对实验中回避交叉测量的能级差,对已有的nS态量子亏损进行了修正。二.通过电场的精密操控,使初始制备的nS态里德堡原子绝热地通过回避交叉,制备及探测了强相互作用下高极性里德原子气体。初始制备的里德堡原子(～500德拜)绝热跃迁到高-l斯塔克态,因此获得了巨大的电偶极矩(～2500德拜)。这些高-l态原子镶嵌在其它处于高-|m|斯塔克态的背景原子中,并与其相互作用,产生m态混合。这种混合使得这些原子获得较高的电离域,从能够通过脉冲场电离法使之与初始态分离并进行探测。三.通过精细操控电场两次通过同一回避交叉,制备了一种新型的里德堡原子干涉仪。原子经过回避交叉的绝热/非绝招过程类似于传统干涉仪中的分束及合束过程。初始制备的两个斯塔克能级在通过能级回避交叉的中心时成为相干叠加态,为这种新型干涉仪的产生提供了基础。通过傅利叶转换分析测量原子干涉信号的频谱,发现干涉频率与斯塔克谱中参与回避交中各能级之间的能量差相对应。在传统的光学激发手段中,由于跃迁选择定则(△l=±1)的限制,无法通过直接激发使中间态原子(P态)跃迁到高-l态。该干涉仪克服了禁戒跃迁的限制,提供了一种测量斯塔克能谱的新方法。本文的创新之处：1.提出了一种对nS态里德堡原子的量子亏损进行修正的方法。该方法利用参与回避交叉能级之间的能量差(～100MHz)来修正,大大地规避了传统方法中测量电离域所带来的误差。2.通过外场操控里德堡原子通过回避交叉,制备和探测了极性里德堡气体。这种方法只需非常小的电场(～1V/cm)即可使初始态(～500德拜)获得巨大的电偶极矩(～2500德拜)。3.通过精密操控电场通过同一回避交叉,制备了一种新型的里德堡原子干涉仪。可利用该方法去探测光学激发光谱中由于禁戒跃迁而无法直接激发的能级。
[Abstract]:The outer electrons are excited Rydberg atoms to the principal quantum number N1) very excited atoms, with strong interaction (~ N4) radiation, long service life (~ N3), polarization rate (~ N7) and other unique properties, which has attracted much attention. Ultra cold Rydberg atoms due to the strong the dipole dipole interaction of the dipole blocking effect, the Rydberg atoms become controllable quantum logic gates, quantum information processing, an ideal medium of single photon source and many body physics, in recent years has become a hot research topic. Based on the original sub cesium medium in magneto optical trap was prepared by temperature -100 K the use of laser cooling and trapping technology, the density of ~ 109cm-3 ultra cold atoms at ultracold Rydberg atoms by using two-photon excitation method, using pulsed field ionization ion detection of Rydberg atoms ionized by atomic mass spectrum. The gate plate on both sides of the external electric field is applied to realize the control of ultra cold Rydberg atoms. Because nS Rydberg states with fractional quantum loss is small, the level is close to (n-4) hydrogenlike multiplets, so in the field is very small in the formation of mixed state and avoid crossing level with the precise measurement of the Rydberg. In the outer field of Stark spectroscopy, a detailed study of the nS (n-4) state and avoid cross hydrogenic states. Based on the experimental measurement and theoretical simulation of avoided crossing comparison, this paper presents a new method for correction of nS state quantum loss; in addition, in high Rydberg Stark state by nS -l atom manipulation of the initial field insulation cloth preparation, a highly polar Rydberg atom gas preparation; finally, through precise regulation two times through the same electric field to avoid cross, preparation of a new type of Rydberg atom interferometer Instrument. Details are as follows: 1. In a magneto-optical trap in the outfield in precision measurement of three level 49S1/2 state and n=45 high -l multiplet formation avoided crossing ion spectra of the two-photon stimulated by quantum simulation. The comparison experiment in cross measurement to avoid the gap on the existing state of quantum nS loss for correction. Two. The control precision of the electric field, the initial preparation of nS Rydberg atoms adiabatically by avoiding cross, preparation and detection of the strong interaction under high polar gas. Reed atom initially prepared Rydberg atoms (~ 500 Debye) adiabatic transition to high -l Starr g state, thereby achieving great the dipole moment (~ 2500 Debye). These states of -l atoms embedded in other -|m| in the high background of stark state atoms, and their interactions, generating M state mixing. This makes these mixed atomic ionization domain from high, can through the veins The pulsed field ionization method and detection and initial state separation. Three. Through the fine manipulation through the same electric field two times to avoid cross, a new type of Rydberg atom interferometer was prepared by atom. Avoid crossing the adiabatic / non beam process process is similar to the traditional trick in the interferometer. Two stark levels initially prepared in the center of the cross level to avoid a coherent superposition state, provide the basis for this new interferometer. Measurement and analysis of atomic interference signal spectrum by Fu Liye transform, frequency spectrum and stark interference found corresponding to the energy level difference in avoidance between the energy exchange in. The traditional optical excitation method, the selection rule (l= + 1) limit, not by direct excitation of atoms in the middle (P state) transition to high -l state. The interferometer overcomes the limitation of forbidden transition, Provide a new method for measuring the stark spectrum. The innovation of this paper: 1. this paper puts forward the method of modifying a nS Rydberg atom quantum loss. By using this method in avoiding cross level difference between energy (~ 100MHz) to correct, greatly avoid the error brought by.2. measurement of ionization domain the traditional method in the field through the manipulation of Rydberg atoms by avoiding cross, preparation and detection of polar Rydberg gas. Electric field this method only needs very small (~ 1V/cm) can make the initial state (~ 500 Debye) huge dipole moment (~ 2500 Debye).3. by precision control by the same electric field avoid crossing, a new type of Rydberg atom interferometer was prepared. The method can be used to detect the level of optical excitation spectrum due to direct excitation transitions.

【学位授予单位】：山西大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O562

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