光学偶极阱中铷原子5S_(1/2)及5P_(3/2)态的AC Stark频移

基于二能级模型和多能级模型,分析计算了由强聚焦高斯光束形成的光学偶极阱中87Rb原子5S1/2态和5P3/2态的AC Stark频移。基于多能级模型,针对在852 nm高斯激光束强聚焦所形成的87Rb原子远失谐光学偶极阱中进行偏振梯度冷却的情形,计算了冷却循环跃迁(5S1/2F=2-5P3/2F′=3)的频移量,结果显示频移对molasses冷却过程产生了重要的影响。同时,计算了5S1/2|F=2,mF=±2〉态和5P3/2|F′=3,mF=±3〉态的AC Stark频移随光学偶极阱激光波长的变化情况,发现在红失谐情况下,对于87Rb原子5S1/2-5P3/2态跃迁不存在魔数波长。     

Cs 39D态Rydberg原子Stark光谱的实验研究

本文从理论和实验上对Cs39D态Rydberg原子在弱电场作用下的Stark效应做了详细研究. 理论上利用数值方法计算了Cs原子39D态的Stark结构;实验上,采用两步激发超冷基态原子获得超冷Rydberg原子,通过场电离的方法获得了39D态的Stark光谱,测量获得α^5/2₂,α^5/2₀,α^3/2₂和α^3/2₀相应的极化率分别为：62(7),－146(13), 73(6) 和－106(20) MHz·V^-2cm²,实验结果与理论相符合. 关键词： Rydberg原子 Stark结构 场电离 极化率     

镓原子的Stark能级结构

里德堡原子的Stark效应在偶极偶极相互作用、量子信息和量子调控等方面具有潜在的应用前景. 本文首先根据零场时镓原子的能级数据, 通过非线性拟合方法获得了镓原子各态的量子亏损, 仔细分析了量子亏损随主量子数的变化特征; 然后利用Numerov算法计算了镓原子的径向波函数; 最后采用矩阵对角化方法, 数值计算了镓原子高里德堡态在场强范围F=0-3000 V·cm^{- 1}时n=7和n=18附近的Stark能级结构. 结果显示在主量子数n=7多重态以上的能级结构中, (n+1)P态的能级接近并大于nD态的能级, 在n=7多重态以下的能级结构中, (n+1)P态的能级接近并小于nD态的能级. 这一现象不同于通常的碱金属原子的Stark结构, 论文对该现象及其他Stark能级结构特征进行了详细分析, 为相关研究工作提供了重要参考价值.     

Study of Ba 6snk Rydberg states in electric field

The autoionization detection is employed to measure the Stark spectra of Ba 6snk Stark states with n from 13 to 15. The Stark maps with M=0 and |M|=1 can be selectively excited by two lasers with different combinations of polarization under different strengths of electric fields. General features of Ba Stark states observed in the experiment are discussed in detail, and the comparisons between M=0 and |M|=1 cases are made. Theoretical calculations based on the perturbation theory are performed to simulate the corresponding experiments, results of which are satisfactory.     

激光冷却铯原子喷泉频标的黑体辐射频移

研究了激光冷却铯原子喷泉频标的黑体辐射频移（包括黑体辐射塞曼频移和黑体辐射斯塔克频移）,推导了频移的计算公式,估算了室温下频移及其不确定度的大小,分析了黑体辐射频移对频标准确度的影响。结果表明：１）室温下黑体辐射塞曼频移可达１０＾－１５量级,在评定铯原子喷泉频标准确度时,需要对此项频移加以修正;２）在利用直流斯塔克效应估算黑体辐射斯塔克频移时,由直流极化率常数ｘ的测量误差导致的黑体辐射斯塔克频移的     

铯原子高激发态Stark能级的数值计算和实验观察

利用数值方法计算了铯原子的Stark结构,经过对氢原子的数值计算与解析结果的对比,确认我们的计算程序是精确的.实验工作在超冷铯原子中完成,利用共振增强多光子电离光谱方法测量了铯原子n=16附近的Stark光谱,理论计算和实验结果相一致.     

铯原子里德堡态Stark能量及电偶极矩的测量和理论计算

里德堡原子由于具有体积大、寿命长、易极化及在外电场中能级易于操控等特点, 已经成为了目前物理学领域研究的热点之一. 本文在磁光阱中实验测量了铯原子15P_3/2和16P_3/2态的Stark光谱,根据光谱给出了15P_3/2和16P_3/2|m|=1/2 Stark态在0-1400 V/cm场强范围适用的Stark 能量和偶极矩的经验性解析表达式; 用数值方法求解薛定谔方程获得了这些态的Stark能量、偶极矩和电子几率密度分布. 电子几率密度分布定性说明了计算的偶极矩矢量的方向是正确的. 计算的Stark能量、偶极矩与实验结果相一致.     

光抽运小型铯束频标中光频移的测量与分析

在弥漫激光场抽运斜入射光检测小型铯原子束频标实验系统上 ,对弥漫激光场产生的散射光所引起的光频移 (主要是交流斯塔克移动 )以及光抽运区产生的荧光引起的光频移对铯束频标准确度的影响作了仔细的实验测量 ,并与理论计算结果作了比较分析。测量结果表明在正常工作条件下 ,散射光引起的光频移小于 - 2× 10 -13 ,荧光引起的光频移值在 0 8× 10 -13 左右 ,这样的光频移对小型光抽运铯束频标来说是可以接受的。     

Dynamical polarizability of atoms in arbitrary light fields: general theory and application to cesium

We present a systematic derivation of the dynamical polarizability and the ac Stark shift of the ground and excited states of atoms interacting with a far-off-resonance light field of arbitrary polarization. We calculate the scalar, vector, and tensor polarizabilities of atomic cesium using resonance wavelengths and reduced matrix elements for a large number of transitions. We analyze the properties of the fictitious magnetic field produced by the vector polarizability in conjunction with the ellipticity of the polarization of the light field.     

Yb原子高激发态的斯塔克光谱

采用ππ偏振激光，通过两步激发和光电离方法，在０－１５４Ｖ／ｃｍ电场范围内，测定了Ｙｂ原子ｎ－１８附近ｍ＝０的斯塔克光谱，首次把包含斯塔克效应的能量矩阵对角化方法推广到Ｙｂ原子，所获得的理论斯塔克图与实验结果基本符合，观察到低场中斯塔克簇随电场增加呈现线性结构以及＾１Ｐ１态与斯塔克簇在抗交叉过程中振子强度发生转移的现象，讨论了结构与量子亏损的关系。     

弱射频场中Rydberg原子的电磁感应透明

在铯原子室温蒸气池中研究了弱射频场中Rydberg原子阶梯型三能级系统的电磁感应透明(EIT)效应.铯原子基态6S_(1/2)、第一激发态6P_(3/2)和Rydberg 48D_(5/2)态形成阶梯型三能级系统,探测光共振作用于6S_(1/2)(F=4)→6P_(3/2)(F′=5)的跃迁,耦合光在Rydberg跃迁线6P_(3/2)(F′=5)→48D_(5/2)附近扫描,形成Rydberg原子EIT.当对铯原子施加一个80 MHz的弱射频电场时,48D_(5/2)Rydberg原子的EIT光谱发生Stark频移和分裂,同时产生由射频场调制Rydberg能级的偶数级边带,测量结果与Floquet理论模拟的结果相符合.同时,改变弱射频电场的频率研究了铯Rydberg能级的自电离效应对Rydberg原子Stark谱的影响,据此,我们提出将电极板置于铯原子蒸气池内的方案以减少自电离效应的影响.在弱射频Stark谱中,mj=5/2的Stark谱与mj=1/2,3/2的二级边带形成多个能级交叉,这些能级交叉点提供了一种基于原子的精确校准射频电场的新方法.     

Theoretical study of slowing supersonic CH3F molecular beams using electrostatic Stark decelerator

We have calculated the Stark effect of CH3F molecules in external electrical fields,the rotational population of supersonic CH3F molecules in different quantum states,and analyse the motion of weak-field-seeking CH3F molecules in a state |J = 1,KM = 1 inside the electrical field of a Stark decelerator by using a simple analytical model.Threedimensional Monte Carlo simulation is performed to simulate the dynamical slowing process of molecules through the decelerator,and the results are compared with those obtained from the analytical model,including the phase stability,slowing efficiency as well as the translational temperature of the slowed molecular packet.Our study shows that with a modest dipole moment(～1.85 Debye) and a relatively slight molecular weight(～34.03),CH3F molecules in a state |J = 1,KM = 1 are a good candidate for slowing with electrostatic field.With high voltages of ±10 kV applied on the decelerator,molecules of 370 m/s can be brought to a standstill within 200 slowing stages.     

蓝移阱中单个铯原子基态磁不敏感态的相干操控

单个中性原子的超精细微波跃迁能级的相干性是基于中性原子量子计算、量子信息处理和量子模拟的基础.我们在实验上利用微波双光子拉曼过程实现了蓝移阱中铯原子基态超精细态|6S1/2,F=3,mF=-1〉和|6S1/2,F=4,mF=1〉间的相干操控,并研究了其相对能级频移随磁场的变化,获得了"魔术"磁场的大小为1.4(2)Gauss(1 Gauss=10-4 T).结果表明,利用魔术磁场可大幅改善超精细态|6S1/2,F=3,mF=-1?和|6S1/2,F=4,mF=1〉之间的相干性,测量到的相干时间可达1.0(1)s.     

Interaction-enhanced double resonance in cold gases

A new type of double-resonance spectroscopy of a quantum gas based on interaction-induced frequency modulation of a probe transition has been considered. Interstate interaction of multilevel atoms causes a coherence-dependent collisional shift of the transition between the atomic states |1〉 and |2〉 due to a nonzero population of the state |3〉. Thus, the frequency of the probe transition |1〉?|2〉 experiences oscillations associated with the Rabi oscillations between the states |1〉 and |3〉 under continuous excitation of the drive resonance |1〉?|3〉. Such a dynamic frequency shift leads to a change in the electromagnetic absorption at the probe frequency and, consequently, greatly enhances the sensitivity of double-resonance spectroscopy as compared to traditional “hole burning”, which is solely due to a decrease in the population of the initial state |1〉. In particular, it has been shown that the resonance linewidth is determined by the magnitude of the contact shift and the amplitude of the drive field and does not depend on the static field gradient. The calculated line shape and width agree with the low-temperature electron-nuclear double-resonance spectra of two-dimensional atomic hydrogen.     

Cs原子里德伯态Stark能级场电离阈值与｜ml｜关系的测定

报道Ｃｓ原子里德伯态Ｓｔａｒｋ能级场电离阈值与｜ｍ_l｜依赖关系的实验研究结果，从实验上同时测得Ｃｓ原子｜ｍ_l｜＝０，１，２三种态的电离阈值表达式。 关键词：     

The experimental study of Ba 6pjnk |M| = 0, 1 autoionizing series

The spectra of the Ba 6pnk autoionizing Stark states with |M| = 0, 1, converging to the 6p_1/2⁺ and 6p_3/2⁺ ionization thresholds, are measured as a function of the electric field strength F. Several 6p_jnk Stark manifolds with n = 13–15 have been systematically studied in order to explore their characteristics of configuration interaction. Experimental results are analyzed by fitting them to the Lorentzian profile, from which the positions and widths are determined. Different spectroscopic properties between the Ba 6p_1/2nk and 6p_3/2nk autoionizing Stark states are investigated. Comparison between the Ba 6p_jnk autoionizing Stark states with |M| = 0 and those with |M| = 1 are made.     

环境辐射对原子高激发能级Stark态寿命的影响

在外电场中用激光两步激发使Na原子在待测Stark态（n=17，m=0）上实现布居．用延迟脉冲场电离方法测量了部分Stark态的寿命及环境黑体辐射对其实际寿命的影响，并与理论计算值作了比较．实验和计算表明：对n=17的Stark簇各能态，室温下环境黑体辐射引起的受激跃迁对其寿命的影响与自发辐射跃迁已达同一数量级．寿命越长的Stark态，黑体辐射的影响程度越大，这一因素连同Stark混合效应均使同一Stark簇内各能态实际寿命的差异变小． 关键词：     

钠原子能级的斯塔克结构

本文报道钠在主量子数n=12,13,14附近能区的斯塔克(stark)效应,外场从0～8kV/cm.观察到随着电场的增加,角动量小的项并入线性斯塔克簇,且不同|m|的能级简并解除.对实验结果进行了分析讨论.     

铯原子nP_(3/2)(n=70—94)里德伯态的紫外单光子激发及量子亏损测量

基于成熟的光纤激光器、光纤放大器及高效激光频率转换技术,我们在实验中研制了一套瓦级输出的窄线宽连续波单频可调谐318.6 nm紫外激光系统,并在室温铯原子气室中实现了6S_(1/2)—nP_(3/2)(n=70—94)单光子跃迁里德伯激发.借助由铯原子6S_(1/2)(F=4)基态、6P_(3/2)(F′=5)激发态和nP_(3/2)(n=70—94)里德伯态构成的V型三能级系统,通过频率锁定于铯原子6S_(1/2)(F=4)—6P_(3/2)(F′=5)超精细跃迁的852.3 nm探测光束的吸收减弱信号获得了里德伯态的信息,并利用高精度波长计测量了铯原子nP_(3/2)(n=70—94)里德伯态的量子亏损值.经过与理论计算值的变化趋势进行对比,我们认为由于原子气室的里德伯屏蔽效应并不能完全屏蔽外部直流电场,铯原子气室内存在残余的直流电场,影响了对里德伯态的量子亏损值的实验测量.利用残余直流电场的Stark效应理论模型及其与有效主量子数n*的依赖关系,对铯原子里德伯态的量子亏损实验测量值进行了修正.修正后的铯原子nP_(3/2)(n=70—94)态量子亏损测量值为3.5591±0.0007,与理论计算值相吻合.     

Demonstration of three-dimensional electrostatic trapping of state-selected Rydberg atoms

A three-dimensional trap for Rydberg atoms in selected Stark states has been realized experimentally. H atoms seeded in a supersonic expansion of Ar are excited to the low-field seeking n=30, k=25, |m|=0, 2 Rydberg-Stark states, decelerated from a mean initial velocity of 665 m/s to zero velocity in the laboratory frame and loaded into a three-dimensional electrostatic trap. The motion of the cold Rydberg atom cloud in the trap and the decay of the trapped atoms have been studied by pulsed electric field ionization and imaging techniques.