Exciton-polaritons in a 2D hybrid organic-inorganic perovskite microcavity with the presence of optical Stark effect

This study investigates the properties of exciton-polaritons in a two-dimensional(2D)hybrid organic-inorganic perovskite microcavity in the presence of optical Stark effect.Through both steady and dynamic state analyses,strong coupling between excitons of perovskite and cavity photons is revealed,indicating the formation of polaritons in the perovskite microcavity.Besides,it is found that an external optical Stark pulse can induce energy shifts of excitons proportional to the pulse intensity,which modifies the dispersion characteristics of the polaritons.

基于里德伯原子Stark效应射频电场测量灵敏度研究

里德伯原子极化率大,在外加电场作用下原子能级发生Stark分裂和频移,可实现里德伯原子高灵敏电场传感器的研究.采用Shirley的简化不含时Floquet哈密顿量模型,计算了Cs里德伯原子的AC Stark能谱,修正后与实验上测得的弱场中Cs里德伯原子的DC Stark离子能谱拟合,在获得60D_(5/2)和70D_(5/2)里德伯原子态极化率αDC的同时实现低频弱场灵敏度的计算.并计算了Cs里德伯原子60D_(5/2)态频率在0—500 GHz范围内振荡电场中的AC Stark能级频移量,对里德伯原子传感器在其宽光谱范围内的灵敏度进行定量分析,实现任意场频率最佳灵敏度的计算,为里德伯原子传感器的研究提供理论基础.

Development of an upgraded motional Stark effect diagnostic system on EAST tokamak

A new multi-channel motional Stark effect(MSE)diagnostic system has been developed on the upgraded EAST tokamak,which was installed on the port C to observe a tangential neutral beam.A telecentric imaging lens was deployed to ensure uniform illumination from the core to the boundary.A square fiber head which contained 23 fiber bundles was mounted to this imaging lens;each fiber bundle contained 19 fibers and two of them were assigned to CXRS and BES spectrometer,respectively.The angle tuning method was used for matching the Doppler shift of theσcomponent’s wavelength which was caused by the beam voltage.At the present stage,the MSE system only contains ten channels that would be extended to 23 channels in the future,covering a measurement range from R=1.8 to R=2.27 m with a temporal resolution of 10 ms and a spatial resolution of3 cm.The polarization angle-constrained q profiles and current density profiles were reconstructed with EFIT equilibrium reconstructions.In the sawtooth discharges,the q=1 surface position was validated by the ECE signals,which further verified the rationality of the MSE measurement.

High-level Stark Effect and Spectrum of Spherical Nanometer System

In the electric field and layer-to-layer interaction energy, the law of split-level of high-level Stark effect of spherical nanometer system is explored as well as the frequency of spectrum, intensity and size effect of coefficient of spontaneous radiation. Taking three layers CdS/HgS spherical nanometer system as an example, the influence of the electric field and layer-to- layer interaction energy is explored on Stark effect and spectrum. The results show that in the Stark effect system, the energy level is split based on 1, 3, ..., （2n-1）, when it is in the electric field only, similar to the hydrogen atoms; and in the electric field and layer-to-layer interaction, it is split based on 1, 4, ~ -., n2; with the quantum transition, the frequency of the spectrum decreases with the increasing size of the system; apart from a few spectral lines, the intensity of most spectral lines will decreased as the size increases; while the coefficient of spontaneous radiation will increase with the increasing size; the electric field will cause the changes of spectrum frequency; its spectrum frequency shift is proportional to the square of the electric field intensity; apart from a few spectral lines, the frequency shift of spectral lines that is caused by the electric field and layer-to-layer interaction will decrease as the size increases; the interaction will make the level of electronic energy level lower slightly （the order of magnitude is between 10-7-10-9 eV）, the slightly increased spectrum intensity and the slightly increased value of coefficient of spontaneous radiation, but it will not influence the frequency of spectrum, intensity, and the trend that coefficient of spontaneous radiation changes with the size; when the size is smaller, the layer-to-layer interaction effect will be significant.

Pressure influence on the Stark effect of impurity states in a strained wurtzite GaN/Al_xGa_(1-x)N heterojunction

A variational method is adopted to investigate the properties of shallow impurity states near the interface in a free strained wurtzite GaN/AlxGa1-xN heterojunction under hydrostatic pressure and external electric field by using a simplified coherent potential approximation. Considering the biaxial strain due to lattice mismatch or epitaxial growth and the uniaxial strains effects, we investigated the Stark energy shift led by an external electric field for impurity states as functions of pressure as well as the impurity position, A1 component and areal electron density. The numerical result shows that the binding energy near linearly increases with pressure from 0 to 10 GPa. It is also found that the binding energy as a function of the electric field perpendicular to the interface shows an un-linear red shift or a blue shift for different impurity positions. The effect of increasing x on blue shift is more significant than that on the red shift for the impurity in the channel near the interface. The pressure influence on the Stark shift is more obvious with increase of electric field and the distance between an impurity and the interface. The increase of pressure decreases the blue shift but increases the red shift.

Screening influence on the Stark effect of impurity states in strained wurtzite GaN/Al_xGa_(1-x)N heterojunctions under pressure

The screening effect of the random-phase-approximation on the states of shallow donor impurities in free strained wurtzite GaN/AlxGa1-xN heterojunctions under hydrostatic pressure and an external electric field is investigated by using a variational method and a simplified coherent potential approximation. The variations of Stark energy shift with electric field, impurity position, A1 component and areal electron density are discussed. Our results show that the screening dramatically reduces both the blue and red shifts as well as the binding energies of impurity states. For a given impurity position, the change in binding energy is more sensitive to the increase in hydrostatic pressure in the presence of the screening effect than that in the absence of the screening effect. The weakening of the blue and red shifts, induced by the screening effect, strengthens gradually with the increase of electric field. Furthermore, the screening effect weakens the mixture crystal effect, thereby influencing the Stark effect. The screening effect strengthens the influence of energy band bending on binding energy due to the areal electron density.

Development of signal analysis method for the motional Stark effect diagnostic on EAST

A pilot single-channel Motional Stark Effect（MSE） diagnostic has been developed on EAST since 2015. The dual photo-elastic modulators（PEM） were employed to encode the polarization angle into a time-varying signal. The pitch angle was related to the ratio of modulation amplitude at the second harmonic frequency. A digital harmonic analyzer（DHA） technique was developed for extracting the second harmonic amplitude. The results were validated with a hardware phase lock-in amplifier, and is also consistent with the software dual phase-locking algorithm.

Stark effect of the hyperfine structure of ICl in its rovibronic ground state:Towards further molecular cooling

Hyperfine structures of IC1 in its vibronic ground state due to the nuclear spin and electric quadruple interactions are determined by diagonalizing the effective Hamiltonian matrix. Furthermore, the Stark sub-levels are precisely determined as well. The results are helpful for electro-static manipulation （trapping or further cooling） of cold IC1 molecules. For example, an electric field of 1000 V/cm can trap IC1 molecules less than 637μK in the lowest hyperfine level.

Quantum Fisher Information of Two-Level Atomic System under the Influence of Thermal Field, Intrinsic Decoherence, Stark Effect and Kerr-Like Medium

In this paper, we have proposed the numerical calculations to study the quantum entanglement (QE) of moving two-level atom interacting with a coherent and the thermal field influenced by intrinsic decoherence (ID), Kerr medium (non-linear) and the Stark effect. The wave function of the complete system interacting with a coherent and the thermal field is calculated numerically affected by ID, Kerr (non-linear) and Stark effects. It has been seen that the Stark, Kerr, ID and the thermal environment have a significant effect during the time evolution of the quantum system. Quantum Fisher information (QFI) and QE decrease as the value of the ID parameter is increased in the thermal field without the atomic movement. It is seen that QFI and von Neumann entropy (VNE) show an opposite and periodic response in the presence of atomic motion. The non-linear Kerr medium has a more prominent and significant effect on the QE as the value of the Kerr parameter is decreased. At smaller values of the non-linear Kerr parameter, the VNE increases, however, QFI decreases, so QFI and VNE have a monotonic connection with one another. As the value of the Kerr parameter is increased, the effect of non-linear Kerr doesn’t stay critical on both QFI and QE. However, a periodic response of QE is seen because of the atomic movement which becomes modest under natural impacts. Moreover, it has been seen that QFI and QE rot soon at the smaller values of the Stark parameter. However, as the value of the Stark parameter is increased, the QFI and QE show periodic response even when the atomic movement is absent.

Stark and Kerr Effects on the Dynamics of Moving N-Level Atomic System

We have investigated numerically the dynamics of quantum Fisher information (QFI) and quantum entanglement (QE) for N-level atomic system interacting with a coherent field in the presence of Kerr (linear and non-linear medium) and Stark effects. It is observed that the Stark and Kerr effects play a prominent role during the time evolution of the quantum system. The evolving quantum Fisher information (QFI) is noted as time grows under the non-linear Kerr medium contrary to the QE for higher dimensional systems. The effect of non-linear Kerr medium is greater on the QE as we increase the value of Kerr parameter. However, QFI and QE maintain their periodic nature under atomic motion. On the other hand, linear Kerr medium has no prominent effects on the dynamics of N-level atomic system. Furthermore, it has been observed that QFI and QE decay soon under the influence of Stark effect. In short, the N-level atomic system is found prone to the change of the Kerr medium and Stark effect for higher dimensional systems.

Mixed-field effect at the hyperfine level of^(127)I^(79)Br in its rovibronic ground state:Toward field manipulation of cold molecules

The mixed-field effect at the hyperfine level of the rovibronic ground state of the^(127)I^(79)Br(X^(1)Σ,v=0,J=0)molecule is computed on the J-I uncoupled basis of|JM_(J)I_(1)M_(1)I_(2)M_(2)>,where J is the molecular total angular momentum excluding nuclear spin,M_J is the projection number of J,I_(1) and I_(2) are the nuclear spins of the iodine and bromine atoms,and M_(1) and M_(2) are the projection numbers of I_(1) and I_(2),respectively.When the two applied electric and magnetic fields are parallel,the perturbations are rare and only one perturbation is observed in a relatively large field regime in our computation range.However,when the two fields are off-parallel,the perturbations increase significantly and some sublevels show the Feshbach-like resonance phenomenon.Therefore,such sublevels transit between weak-field seeking and strong-field seeking repeatedly,which can be utilized to enhance or suppress cold molecular collision and chemical reaction rates.Such behavior of the molecular hyperfine structure in the mixed off-parallel fields may also be utilized to construct an electric-field-assisted anti-Helmholtz magnetic trap for cold molecules and to realize evaporative cooling of cold molecules(sub-mK)into the ultracold regime(μK).

针-极板内氦气等离子体射流电场监测研究

小空间下强电场测量方法的研究是一个难点,借助谱线的Stark效应,选择合理的原子或离子,可在无干扰的情况下完成测量。设计了一套大气压纳秒脉冲放电实验装置,通过针-极板放电产生强电场,试验He 447.1 nm谱线在不同放电电压下产生的强电场下的分裂情况,在谱线展宽难以直接通过观察谱线的方法得到的情况下,借助非线性最小二乘法,分析谱线的允许分量、禁止分量和场无关分量,求出对应的波长偏移量,由此得出电场大小。根据Mason公式,在能量等效的基础上,实验结果符合理论预期,通过该方法可以实现对小空间内强电场的测量。经分析,理论与实验结果之间的偏差可能是由氦气在被击穿时产生等离子体形成的屏蔽导致。

氢原子低能级的Stark效应

用微扰法计算了氢原子低能级的Stark效应 ,基态精确到二级修正 ,能级产生移动 ;第一激发态、第二激发态精确到一级修正 ,能级产生分裂 ,简并部分解除 .

用相位分析方法计算交流Stark效应

定态波函数的相位变化极其简单。当原子受到含时间的微扰作用时，任一叠加态中各定态波函数的振幅和相位都随时间作复杂变化。振幅的变化描述跃迁几率，相位的变化体现为原子的能级移动。本文用分析相位的变化来计算能级移动。

氢原子一级Stark效应能级的解析式

根据简并态微扰论、球坐标系中氢原子波函数的性质,得到任意能级下氢原子一级Stark效应能级计算的简单方法,并计算了n=5的能级修正值,由此得到了氢原子一级Stark能级的解析式.

C_2H_2分子受激Raman光谱中的光学Stark效应研究

本文研究了 C2 H2 分子受激 Raman光谱 (SRS)中的光学斯塔克 (Stark)效应 ,同时还研究了激光功率以及单一转动态量子数 J与 Stark效应的关系 .实验表明 :C2 H2 分子在高强度激光电场作用下 ,它的 SRS由于光学 Stark效应产生明显的非对称加宽 ,利用 Stark线型加宽数值模拟 ,从理论上计算了 Raman光谱线型 ,与实验的 SRS线型比较 ,二者符合程度相当好 .

Stark效应对双光子Jaynes－Gummings模型中原子辐射谱的影响

本文研究了Ｓｔａｒｋ效应对双光子Ｊａｙｎｅｓ－Ｃｕｍｍｉｎｇｓ模型中原子辐射谱的影响，结果表明：Ｓｔａｒｋ效应使得原子的辐射谱偏离关于中心频率的对称性，各峰的相对高度发生了明显的变化。

用二能级理论解释交流Stark效应

用二能级理论的Ｒａｂｉ解说明交流Ｓｔａｒｋ效应。既从原子电偶极矩随外场变化的角度。

光泵远红外激光AC Stark分裂的频谱特性

利用三能级近似和多组三能级近似模型的光泵远红外激光增益解析表达式，通过迭代运算得到了ＣＯ２－１０Ｒ（８）泵浦ＮＨ３分子远红外激光的工作气压与输出光强的关系曲线和ＡＣＳｔａｒｋ分裂的频谱曲线，以及最佳工作气压的理论值．并在实验中测出了ＮＨ３分子２８１μｍ远红外信号的频谱特性和最佳工作气压．

Stark效应对压缩相干光场作用下原子的偶极压缩效应的影响

该文研究了包括Ｓｔａｒｋ效应时，双光子Ｊａｙｎｅｓ－Ｃｕｍｍｉｎｇｓ模型与单模压缩相干光场发生相互作用的二能级原子的偶极压缩效应；讨论了光场参数对压缩效应的影响．