铷离子-铷原子混合阱飞行时间谱的拟合和仿真模拟

离子-原子混合阱是研究带电粒子-中性粒子低温反应的理想平台,直接甄别反应产物最准确的方法是带电粒子飞行时间谱,飞行时间谱峰的强度、位置(飞行时间)和宽度给出了相应带电粒子的强度和动能(温度)等信息.本文通过分析和模拟铷离子-原子混合阱中的飞行时间谱,获得了不同荷质比的离子绝对强度和温度等信息.具体说,首先使用Gumbel型极值分布函数飞行时间谱的谱峰,获得谱峰强度、位置和宽度等信息.然后对实验建模得到耦合的原子数和总带点离子的速率方程,用这些速率方程拟合实验数据,并结合实验测量到的绝对原子数,获得绝对的离子数强度.由此提供了一种标定探测器(本文使用的是微通道板)的方法.改变电离激光的波长和强度得到的标定因子是一致的,表明了这种方法的可靠性.此外,利用COMSOL Multiphysics模拟实验的飞行时间谱,仿真模拟结果表明离子动能大,谱峰宽度窄.本文对飞行时间谱的强度和宽度分析为冷原子光电离过程的离子-原子反应碰撞和带电粒子温度弛豫奠定了基础.     

An all-optical phase detector by amplitude modulation of the local field in a Rydberg atom-based mixer

Recently, a Rydberg atom-based mixer was developed to measure the phase of a radio frequency (RF) field. The phase of the signal RF (SIG RF) field is down-converted directly to the phase of a beat signal created by the presence of a local RF (LO RF) field. In this study, we propose that the Rydberg atom-based mixer can be converted to an all-optical phase detector by amplitude modulation (AM) of the LO RF field; that is, the phase of the SIG RF field is related to both the amplitude and phase of the beat signal. When the AM frequency of the LO RF field is the same as the frequency of the beat signal, the beat signal will further interfere with the AM of the LO RF field inside the atom, and then the amplitude of the beat signal is related to the phase of the SIG RF field. The amplitude of the beat signal and the phase of the SIG RF field show a linear relationship within the range of 0 to π/2 when the phase of the AM is set with a difference π/4 from the phase of the LO RF field. The minimum phase resolution can be as small as 0.6° by optimizing the experimental conditions according to a simple theoretical model. This study will expand and contribute to the development of RF measurement devices based on Rydberg atoms.     

基于冷里德堡原子电磁感应透明的微波电场测量

在磁光阱中利用冷原子温度低,多普勒展宽小的优势获得了窄线宽的里德堡电磁感应透明(EIT)谱峰,结合Autler-Townes分裂效应(EIT-AT分裂)分别测量了多个频率的微波电场强度.结果显示,EIT-AT分裂间距与微波电场强度呈很好的线性关系,EIT-AT分裂方法可测量的微波电场强度线性区的下限可达222μV/cm,这个下限比传统热原子蒸汽池中EIT-AT分裂线性区的下限5 mV/cm提高了大约22倍,这对极弱微波电场的绝对校准非常有帮助.我们进一步利用EIT共振处探测光透过率的变化测量微波电场强度,对应的最小测量值可以小于1μV/cm,相应的灵敏度可达到1μV·cm^-1.Hz^-1/2.这些结果展示了冷原子样品在微波电场测量及其绝对校准方面的优势.     

铥原子收敛于4f~(13)(~2F~?_(7/2))6s(7/2,1/2)~?_4和4f~(13)(~2F~?7/2)6s(7/2,1/2)~?_3偶宇称里德伯系列能级的电子关联效应

本文在多通道量子亏损理论框架下,利用相对论多通道理论,计算了铥原子收敛于4f~(13)(~2F?_(7/2))6s(7/2,1/2)?_4和4f~(13)(~2F?7/2)6s(7/2,1/2)?_3的三个偶宇称里德伯系列.通过将计算结果与美国国家标准与技术研究院数据进行比较,展示了两种类型的电子关联效应:1)里德伯系列之间的相互作用,导致里德伯系列的能级出现整体偏移; 2)一个孤立的干扰态镶嵌在一个里德伯系列中,破坏了该里德伯系列能级的规则性.     

铥原子收敛于4f13(2F7/2o)6s(7/2,1/2)4o和4f13(2F7/2o)6s(7/2,1/2)3o偶宇称里德伯系列能级的电子关联效应

本文在多通道量子亏损理论框架下，利用相对论多通道理论，计算了铥原子收敛于4f¹³（²F_7/2^o）6s（7/2，1/2）₄^o和4f¹³（²F_7/2^o）6s（7/2，1/2）₃^o的三个偶宇称里德伯系列.通过将计算结果与美国国家标准与技术研究院数据进行比较，展示了两种类型的电子关联效应：1）里德伯系列之间的相互作用，导致里德伯系列的能级出现整体偏移；2）一个孤立的干扰态镶嵌在一个里德伯系列中，破坏了该里德伯系列能级的规则性.     

Ultra-High Efficiency Magnetic Transport of SZRb Atoms in a Single Chamber Bose-Einstein Condensation Apparatus

We report the ultra-high efficiency transport of cold ST Ftb atoms using a moving magnetic quadrupole potential generated by three overlapping pairs of fixed coils. The transfer etticiency is better than 97%, which is the highest ever reported to our knowledge. The temperature increase due to heating is less than IO #K when the initial cloud temperature is llO#K. Our setup is similar to the magnetic transferring belt design [Phys. ftev. A 63 （2001）031401（R）], although it is simpler because the push coil is not required. We use it to transport atoms away from a magneto-optical trap to very close to the wall of the glass cell, facilitating future experiments employing three-dimensional optical lattices, high resolution in-situ imaging, and magnetic Feshbach resonances.     

Relativistic Multichannel Treatment of Ionic Rydberg States of Lanthanum

Ionic Rydberg energy levels of lanthanum are calculated from first principles by relativistic multichannel theory within the framework of multichannel quantum defect theory. The present calculated results are in better agreement with the experimental measurements than the previous calculations [J. Phys. B 34 （2001）369] due to the consideration of dynamical polarizations. Moreover, in the experimental spectra achieved by a five-laser resonance excitation via the intermediate state 5d6d^3 F2, a series of weak ionic Rydberg states and some of perturbing states are found and assigned in this work.     

钪原子的自电离里德伯能级3d4s(~1D_2)nf~2D_(3/2),3d4s(~1D_2)nf~2F_(5/2)和3d4s(~1D_2)np~2D_(3/2)的理论研究

在多通道量子亏损理论框架下,利用相对论多通道理论,分别在冻结实近似和考虑偶极极化下计算钪原子的Jπ=(3/2)-,(5/2)-的三个收敛于[Ar]3d4s(1D2)的自电离里德伯系列的能级.对3d4s(1D2)np2D3/2和3d4s(1D2)nf2F5/2这两个系列,计算结果表明,考虑偶极极化效应后,理论计算和实验测量的量子数亏损之差普遍小于0.01.而对3d4s(1D2)nf2D3/2系列,考虑偶极极化效应后的结果和仅考虑冻结实的结果比较接近,理论计算和实验测量的量子数亏损之差普遍在0.04左右.     

NaK低激发态光谱性质和辐射寿命的从头算

本文对NaK的电子结构做了高级从头算. 计算了与三个最低解离极限相关的10个?-S态的势能曲线. 基于计算的势能曲线，得到了束缚?-S态的光谱常数，与实验结果吻合较好. 用半经典散射理论分析了单重态基态X¹Σ⁺和三重态基态a³Σ⁺的最大振动量子数. 研究了包括跃迁偶极矩、夫兰克-康登因子和辐射寿命在内的跃迁特性. 研究结果表明，这种计算方法可以为超冷碱双原子分子实验提供较为可靠的参数估计.     

An Analytical Derivation of a Symmetric Peak with Width Narrower than the Peak Width of the Probing Laser

This work provides an analytical derivation that a symmetric peak with a width narrower than that of the probing laser can appear due to the non-coherent superposition of two Fano-type peaks.