原子能级与共振时间量子化

本文发展了Ｓｃｈｏｍｍｅｒｓ的时间观点，着重讨论了辐射与物质作用过程的时间和共振时间。并通过假定辐射与物质作用过程为时间本征态，推出了共振时间量子化的重要结论。本文还应用共振时间量子化方法讨论了原子光散射，推出了原子能级和原子的价电子逐级电离所形成的所有离子能级普适性解析公式。     

光散射的逆向思考

长期以来人们已习惯于光被物质散射的思考而形成的“光谱物理学”,而对它的逆向思维、即物质(如原子)被‘光’散射的诸多专题问津的较少;其中的某些问题,如物质(如原子)被光(散射)作用的经典物理图像;物质(如原子)被光加(减)速;物质(如原子)被光俘获、陷落、致冷和速度的聚束。此外,密度效应、光场与原子的互作用,(量子化)光(电磁)场对物质(如原子)散射等是近期取得的成果,都将在该文中给出。     

光散射的逆向思考

长期以来人们已习惯于光被物质散射的思考而形成的“光谱物理学”,而对它的逆向思维、即物质(如原子)被‘光’散射的诸多专题问津的较少;其中的某些问题,如物质(如原子)被光(散射)作用的经典物理图像;物质(如原子)被光加(减)速;物质(如原子)被光俘获、陷落、致冷和速度的聚束。此外,密度效应、光场与原子的互作用,(量子化)光(电磁)场对物质(如原子)散射等是近期取得的成果,都将在该文中给出。     

用短程飞行时间吸收谱对铯磁光阱中冷原子温度的测量

介绍采用短程飞行时间吸收谱测量铯原子磁光阱(MOT) 中冷原子温度的基本原理及实验实现.与通常的飞行时间方法不同，采用短程飞行时间吸收谱来测量MOT 中冷原子云的温度.在MOT 区域正下方若干毫米处入射一束圆柱状共振探测光束(实验中对于h=3mm，5mm，8mm的情况均作了研究)，释放冷原子云，在其膨胀和自由下落过程中穿过探测光束，即可由光电探测器测得飞行时间吸收谱，由此推得MOT中冷原子的温度. 关键词： 磁光阱 冷原子 飞行时间 短程飞行时间 铯原子     

软 X射线共振非弹性光散射及其应用

软 X射线共振非弹性光散射是近年来随着高亮度第三代同步辐射出现而发展起来的光散射光谱技术 ,可以用于对多原子构成的分子、凝聚态物质进行位置选择的价电子态结构的研究。与 X射线光电子能谱 ( XPS)或紫外光电子能谱 ( UPS)相比 ,这一光谱方法由于测量样品激发后产生的散射 X射线 ,因而不仅可以获得表面的原子分子信息 ,而且可以用于研究样品体内或掩埋薄层的原子分子。同时这一方法的共振特性使得其可以进行灵敏的元素选择测量。本文将介绍这一光散射光谱技术及其在原子分子物理、表面物理及凝聚态物理中的应用     

近共振三维光学晶格中铯原子温度的参数依赖

介绍了四光束三维近共振光学晶格的方案,在铯原子磁光阱和光学粘团的基础上搭建了近共振光学晶格的光路,实现了光学晶格中冷原子的装载.利用短程飞行时间吸收法测量了近共振光学晶格中冷原子的温度,通过改变晶格的光强和失谐等条件,对近共振光学晶格中铯原子的亚多普勒冷却的参数依赖关系作了实验研究,并与光学粘团作了比较.     

~6Li超冷费米气体宽Feshbach共振散射的动力学演化研究

本文解析研究了~6Li超冷费米气体宽Feshbach共振散射动力学演化过程,将整个散射过程转化为一个单重态和一系列准连续态的散射共振,等效于涉及接触势的散射过程,在原子波包的持续时间内,束缚态中不断地出现原子布居,并将输入的波包非弹性散射到与之耦合的所有通道中。随着相互作用时间的增加,布居数转移幅度越来越大,连续态和束缚态之间的散射概率逐步增加,最终达到碰撞稳态。同时我们定量的计算了在原子散射过程中连续态和束缚态的动力学演化,在散射过程中连续态和束缚态的总概率守恒,连续态和束缚态之间布局数交换发生在散射共振前后的数十纳秒时间内。     

生物大分子的共振光散射光谱

共振光散射技术是一项在普通荧光分光光度计上可实现分析领域中应用的新技术。本文阐述了共振光散射的基本原理 ,分类介绍了在生物大分子研究和测定方面的应用 ,分析了共振散射体系的新发展。     

钠蒸气中的双光子共振三光子电离和双光子混合共振三光子电离

在钠原子－分子混合样品中，分别运用双光子共振三光子电离以及双光子混合共振三光子电离，测得了钠原子４Ｄ态的电离流时间衰减曲线。由电离流与多光子动力学参数的关系，得到了４Ｄ态的光电离截面。     

罗丹明B的共振散射光谱研究

研究了罗丹明B(RhB)的共振光散射的特性与机理。在 pH =- 0 38至 pH 4 10的酸性溶液中 ,共振光散射信号随pH值增大而增强 ,近中性时散射强度达到最大。散射强度随波长的变化不符合瑞利散射定律。RhB的荧光激发光谱与发射光谱有部分重叠 ,共振散射峰处于荧光激发峰和荧光发射峰之间。在三维荧光等高线光谱图中 ,瑞利散射线与荧光等高线相交。在光偏振实验中 ,测得共振散射光的偏振度P≈ 0 1。上述实验结果揭示RhB的共振散射光主要是共振荧光。共振光散射信号随 pH值增大而增强的机理是RhB酸碱平衡移动导致荧光型体的形成。RhB的共振散射峰位于吸收曲线轮廓之中 ,共振光散射受光吸收的影响 ,因此 ,散射光强度与浓度之间不是严格的线性关系。     

Squeezed light from spin-squeezed atoms

We propose to transfer quantum correlations from atoms to light by Raman scattering of a strong laser pulse on a spin-squeezed atomic sample. We prove that the emission is restricted to a single field mode which perfectly inherits the quantum correlations of the atomic system.     

Designing Fano-Like Quantum Routing via Atomic Dipole-Dipole Interactions

Fano-like quantum routing of single photons in a system with two waveguides coupled to two collocated atoms is investigated theoretically. Using a full quantum theory in real space, photonic scattering amplitudes along four ports of the waveguide network are analytically obtained. It is shown that, by adjusting the atomic dipole-dipole interaction, an evident Fano-line shape emerges in the scattering spectra of the single-dot configuration system.Moreover, Fano resonance can also be achieved by varying the atom-waveguide coupling strength and atomic detuning, in the presence of the atomic dipole-dipole interaction. Therefore, the atomic dipole-dipole interaction may be utilized as a possible way to control spectral Fano-like resonance. The feasibility with the experimental waveguide channels is also discussed.     

Collisional stability of fermionic Feshbach molecules

Using a Feshbach resonance, we create ultracold fermionic molecules starting from a Bose-Fermi atom gas mixture. The resulting mixture of atoms and weakly bound molecules provides a rich system for studying few-body collisions because of the variety of atomic collision partners for molecules; either bosonic, fermionic, or distinguishable atoms. Inelastic loss of the molecules near the Feshbach resonance is dramatically affected by the quantum statistics of the colliding particles and the scattering length. In particular, we observe a molecule lifetime as long as 100 ms near the Feshbach resonance.     

Superradiant light scattering from thermal atomic vapors

Superradiant light scattering from noncondensed, thermal atomic vapors was experimentally studied. We found that superradiant gain is independent of quantum degeneracy and determined only by the shape of the atomic cloud and a contained number of atoms. Superradiant pump-probe spectroscopy was also developed to measure the atomic correlation function, revealing the Doppler-width-limited coherence time of the thermal gas and sudden buildup of long-lived coherence below the transition temperature.     

利用V型三能级原子与相干态光场Raman相互作用传送未知奇偶相干态

描述了简并V型三能级原子与单模相干态光场的Raman相互作用，获得了处于激发态单态的原子与相干态光场相互作用的结果。利用探测原子与光场的相互作用将原子和探测光场制备成最大纠缠态，并将原子注入待测任一奇偶相干叠加态，通过原子与待测腔模构成的Bell基矢演化，对原子进行选择性探测，获得奇偶相干叠加态与原子相互作用后可能的量子状态，然后对待测腔场与原子进行联合探测，接着对所测奇偶相干态腔场的量子状态实施么正变换，就将探测腔场制备到待测腔场的初始量子态上，从而实现未知奇偶相干态的隐形传送。     

Collective cooling and self-organization of atoms in a cavity

We theoretically investigate the correlated dynamics of N coherently driven atoms coupled to a standing-wave cavity mode. For red detuning between the driving field and the cavity as well as the atomic resonance frequencies, we predict a light force induced self-organization of the atoms into one of two possible regular patterns, which maximize the cooperative scattering of light into the cavity field. Kinetic energy is extracted from the atoms by superradiant light scattering to reach a final kinetic energy related to the cavity linewidth. The self-organization starts only above a threshold of the pump strength and atom number. We find a quadratic dependence of the cavity mode intensity on the atom number, which demonstrates the cooperative effect.     

Nonlinear spectroscopic effects in quantum gases induced by atom-atom interactions

We consider nonlinear spectroscopic effects—interaction-enhanced double resonance and spectrum instability—that appear in ultracold quantum gases owing to collisional frequency shift of atomic transitions and, consequently, due to the dependence of the frequencies on the population of various internal states of the particles. Special emphasis is put to two simplest cases, (a) the gas of two-level atoms and (b) double resonance in a gas of three-level bosons, in which the probe transition frequency remains constant.     

The scattering of slow atoms by light

A kinetic equation has been obtained describing the motion of atoms in a resonant field of standing light wave. This equation is used to describe the scattering of atoms for conditions close to experimental ones [1]. It is shown that the dependence of atomic scattering has a dip at the resonance frequency of the field.     

Anomalous spatial concentration of atoms in the field of a standing light wave

The stationary momentum and coordinate distributions of two-level atoms in the field of a one-dimensional standing light wave have been studied. A qualitatively new effect—the predominant concentration of atoms outside of the minima of the optical potential—has been detected in the regime of moderate saturation of an atomic transition and red frequency detuning. This effect has been qualitatively interpreted. Calculations have been performed using the quantum kinetic equation for the atomic density matrix with the complete inclusion of recoil and localization effects in an arbitrary-intensity light field. In addition to theoretical significance, the results can be useful for atomic nanolithography and frequency standards based on optical gratings.