Stark spectrum of barium in highly excited Rydberg states

We present observations of Stark spectra of barium in highly excited Rydberg states in the energy region around n = 35. The one-photon excitation concerns the π transition. The observed Stark spectra at electric fields ranging from 0 to 60 V·cm-1 are well explained by the diagonalization of the Hamiltonian incorporating the core effects. From the Stark maps, the anti-crossings between energy levels are identified experimentally and theoretically. The time of flight spectra at the specified Stark states are recorded, where the deceleration and acceleration of barium atoms are observed. This is very consistent with the prediction derived from the Stark maps from the point of view of energy conservation.     

STARK STRUCTURE OF THE RYDBERG STATES OF ALKALINE-EARTH ATOMS

The Stark effects of the Rydberg states in the alkaline-earth atoms are studied theoretically. Using a method similar to the treatment of alkali atoms, the properties of the Stark states of Mg, Ca, Sr and Ba atoms in the regions far away from the perturbers are investigated. The Stark maps for Mg (n=16, M=0), Ca (n=10, M=0), Sr (n=12, M=0) and Ba (n=13, |M|=0,1) are presented. Topics such as the general methods of calculation, the treatment of fine structure, and the structure of level anti-crossings are discussed. The comparison between the theoretical and experimental Stark maps is satisfactory.     

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.     

斯塔克效应对两模双光子J-C模型腔场谱的影响

研究了斯塔克(Stark)效应对两模双光子Jaynes-Cummings(J-C)模型腔场谱的影响,推导计算出了腔场处于光子数态时腔场谱的计算公式和数值结果,讨论了斯塔克效应和初始场强对腔场谱的影响。发现斯塔克效应在弱场条件下对腔场谱线的频率和强度都有明显的影响,破坏了谱结构的对称性,使两模的谱线更加丰富。初始场较强时斯塔克效应对谱线的影响较弱。模Ⅰ为真空场、模Ⅱ初始场强递增时,斯塔克效应使模Ⅱ的高频峰受到较强的抑制作用,其低频峰在初始场较弱时受到抑制,初始场较强时又有强化作用,初始场更强时,模Ⅱ的谱线退化为经典的共振荧光谱,与无斯塔克效应的情况基本相同。     

Stark效应对J-C模型腔场谱的影响

研究了计及Stark效应的J-C模型的腔场谱,通过求解本征方程导出了腔场谱的计算公式,给出了腔场处于光子数态时的数值结果,讨论了Stark效应和初始场强对标准J-C模型腔场谱的影响.发现在初始场为真空场时,两个Rabi峰的高度相等,随着Stark位移参数的增大,两峰都向低频方向移动,且频差逐渐增大;在初始场较强的情况下,Stark移动参数增大时会导致双峰的对称性消失,通过测量两峰的相对高度也可确定Stark位移参数的大小;在Stark效应较强初始场递增的情况下两峰仍向左移,但峰间距越来越小;在弱场情况下,Stark效应使两峰呈现左高右低或左低右高的峰结构.总之,改变Stark位移参数β1、β2的大小以及初始场强的强弱,可得到不同的谱线结构.     

Control of entanglement between two atoms by the Stark shift

Considering a quantum model consisting of two effective two-level atoms and a single-mode cavity,this paper investigates the entanglement dynamics between the two atoms,and studies the effect of the Stark shift on the entanglement.The results show that,on the one hand the atom-atom entanglement evolves periodically with time and the periods are affected by the Stark shift;on the other hand,the two atoms are not disentangled at any time when the Stark shift is considered,and for large values of the Stark shift parameter,the two atoms can remain in a stationary entangled state.In addition,for the initially partially entangled atomic state,the atom-atom entanglement can be greatly enhanced due to the presence of Stark shift.These properties show that the Stark shift can be used to control entanglement between two atoms.     

不同微场分布函数对Stark加宽和频移的影响

分别采用Holtsmark,Neutral Point,Nearest-Neighbor和Mayer模型微场分布函数对Stark线型进行了研究,进而得到相应微场函数下的Stark加宽和频移,研究了4种不同的微场分布函数对Stark加宽和频移的影响。研究结果表明,在电子加宽参数不变时,4种微场分布函数对Stark加宽和频移的影响随离子加宽参数的增加而增加;在离子加宽参数不变时,4种微场分布函数对Stark加宽和频移的影响随电子加宽参数的增加而增加;特别是,当离子加宽参数较大时,Mayer模型微场分布函数对Stark加宽和频移的影响异常明显。这说明,微场分布函数对谱线的加宽和频移的影响在离子与离子碰撞剧烈的等离子体环境中尤其显著, 在这样的等离子体环境中,进行等离子体诊断时,选择合适的微场分布函数非常重要。结果对等离子体诊断有一定参考价值。     

GaAs半导体量子箱中电子的斯塔克效应

在有效质量近似下,利用变分法研究了在GaAs半导体量子箱中电子能量的斯塔克效应.结论表明：电场平行于量子箱的中心轴时,斯塔克能移只与量子箱高度有关;电场垂直于中心轴时,斯塔克能移仅仅与它的截面尺寸有关.当电场方向与中心轴夹角为任意角时,斯塔克能移与高度和截面都有关.同时在低场和高场极限下,理论上分析了电场大小和量箱尺寸对斯塔克能移的影响.     

激光诱导Ni等离子体发射光谱的空间演化特性研究

在350～600 nm波长范围内测定了激光烧蚀Ni等离子体中Ni原子的空间分辨发射光谱.测定了385.83 nm发射光谱线的相对强度和STARK展宽及其随径向的变化特性.结果表明,在沿激光束方向上,当距离靶表面0～2.5 mm范围内变化时,谱线的STARK展宽和谱线的强度都随距靶面距离的增大先增大,但增大到最大值后随距离的进一步增大而减小.谱线强度和STARK加宽的最大值都出现在离靶面约1.5 mm处.     

激光诱导Ni等离子体发射光谱的空间演化特性研究

在350- 600nm 波长范围内测定了激光烧蚀Ni等离子体中Ni原子的空间分辨发射光谱.测定了385.83 nm发射光谱线的相对强度和STARK展宽及其随径向的变化特性。结果表明, 在沿激光束方向上, 当距离靶表面0-2.5mm范围内变化时,谱线的STARK展宽和谱线的强度都随距靶面距离的增大先增大,但增大到最大值后随距离的进一步增大而减小。谱线强度和STARK加宽的最大值都出现在离靶面约1.5mm处。     

四能级系统中ac-Stark分裂研究

提出一双光场作用下的四能级系统,并对四能级模型的共振荧光谱作了详尽的研究.原子的共振荧光谱随Rabi频率的变化展示出能级的acStark分裂,且在很大参量范围内光谱具有这一特性.但当只有一个激发通道时不产生acStark分裂.在一定的条件下原子的共振荧光谱出现了两条黑线(darkline).可以认为acStark分裂的产生是多通道量子干涉的结果.利用缀饰态理论对acStark分裂给出很好的解释 关键词： 四能级系统模型 ac-Stark分裂 黑线(darkline) 多通道量子干涉     

GaAs半导体量子箱中电子的斯塔克效应

在有效质量近似下,利用变分法研究了在GaAs半导体量子箱中电子能量的斯塔克效应.结论表明:电场平行于量子箱的中心轴时,斯塔克能移只与量子箱高度有关;电场垂直于中心轴时,斯塔克能移仅仅与它的截面尺寸有关.当电场方向与中心轴夹角为任意角时,斯塔克能移与高度和截面都有关.同时在低场和高场极限下,理论上分析了电场大小和量箱尺寸对斯塔克能移的影响.     

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.     

Spontaneous emission of the non-Wiener type

The spontaneous emission of a quantum particle and superradiation of an ensemble of identical quantum particles in a vacuum electromagnetic field with zero photon density are examined under the conditions of significant Stark particle and field interaction. New fundamental effects are established: suppression of spontaneous emission by the Stark interaction, an additional “decay” shift in energy of the decaying level as a consequence of Stark interaction unrelated to the Lamb and Stark level shifts, excitation conservation phenomena in a sufficiently dense ensemble of identical particles and suppression of superradiaton in the decay of an ensemble of excited quantum particles of a certain density. The main equations describing the emission processes under conditions of significant Stark interaction are obtained in the effective Hamiltonian representation of quantum stochastic differential equations. It is proved that the Stark interaction between a single quantum particle and a broadband electromagnetic field is represented as a quantum Poisson process and the stochastic differential equations are of the non-Wiener (generalized Langevin) type. From the examined case of spontaneous emission of a quantum particle, the main rules are formulated for studying open systems in the effective Hamiltonian representation.     

Some regularities within the Stark widths and shifts of resonance ion lines from Li to Ca

A periodic dependence of the Stark widths and shifts of resonance lines, for singly- and doubly-ionized elements, has been found on nuclear charge number Z. These periodicities were found for Griem's theoretical values of the Stark parameters of resonance lines of some singly charged ions from Li to Ca; for other singly- and doubly- charged ions, this parameter was calculated from Griem's semiempirical formula. The dependence of the Stark parameters of the resonance lines on atomic polarizability X has been determined and used to estimate Stark widths and shifts for other singly-charged ions. These values are compared with estimates derived form Griem's semiempirical formula for the Gaunt factor g = 0.2.     

High precision quantum control of single donor spins in silicon

The Stark shift of the hyperfine coupling constant is investigated for a P donor in Si far below the ionization regime in the presence of interfaces using tight-binding and band minima basis approaches and compared to the recent precision measurements. In contrast with previous effective mass-based results, the quadratic Stark coefficient obtained from both theories agrees closely with the experiments. It is also shown that there is a significant linear Stark effect for an impurity near the interface, whereas, far from the interface, the quadratic Stark effect dominates. This work represents the most sensitive and precise comparison between theory and experiment for single donor spin control. Such precise control of single donor spin states is required particularly in quantum computing applications of single donor electronics, which forms the driving motivation of this work.     

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。     

Measurement of the dipole moment of CF3CN

The Stark effect was observed for K = 0 and K = 1, J = 1 → 2 transitions in CF₃CN. Measurements were made in a Stark modulated microwave spectrometer. The dipole moment obtained was μ = 1.262 ± 0.010 D. An analysis of the effects of electric field inhomogeneities on the observed Stark shifts for K = 0 and K = 1 states is included. Appropriate corrections are given for measuring linear Stark effects in a standard waveguide cell calibrated using a molecule with second-order Stark effect.     

Spectroscopic properties of Ba 6pjnk autoionizing Stark series

With a combination of the isolated core excitation (ICE) technique and a proper polarization configuration of three lasers, both the 6p_1/2nk and 6p_3/2nk autoionizing Stark states excited from the 6snk Stark states with have been measured for the first time. The experimental results are analyzed by fitting them to the Lorentzian profiles, from which the positions and widths are determined at various electric-field strengths. The experimental results indicate that the 6p_1/2nk and 6p_3/2nk autoionizing Stark states have different spectroscopic properties due to the difference of their cores.     

Measurement of the Stark Broadening of Atomic Emission Lines in Non–Optically Thin Plasmas by Laser‐Induced Breakdown Spectroscopy

We propose a new method for determining the Stark broadening of atomic emission lines using laser‐induced breakdown spectroscopy. The method allows the determination of the Stark broadening in non–optically thin plasmas, through the introduction of a correction for self‐absorption. Couples of lines of the same species are considered. If one of the Stark broadenings is known, the determination of the other does not require the measurement of the electron density of the plasma. Examples are given for the application of the proposed method to the measurement of the Stark broadening of several aluminum emission lines (Al I at 308.2 nm, Al I at 394.4 nm, and Al I at 396.2 nm).