激光冷却和捕陷中性原子

深入地论述了激光冷却和捕陷原子研究的意义,系统地介绍了激光冷却和捕陷中性原子的历史发展、物理机制及其实验实现方法,并重点介绍了激光冷却和中性原子捕陷的两个重要应用－－原子波激射和原子喷泉。     

激光冷却和捕陷中性原子①

深入地论述了激光冷却和捕陷原子研究的意义,系统地介绍了激光冷却和捕陷中性原子研究的历史发展、物理机制及其实验实现方法,并重点介绍了激光冷却和中性原子捕陷的两个重要应用--原子波激射和原子喷泉.     

激光冷却与捕陷原子的方法——1997年诺贝尔物理奖介绍

介绍了１９９７年诺贝尔物理奖的获奖工作———激光冷却与捕陷原子的方法，其中主要有光学粘团、亚多普勒冷却、亚反冲冷却、激光原子阱等．叙述了它们的物理原理、重要意义及其应用．     

激光冷却与捕陷原子的方法

介绍了１９９７年诺贝尔物理奖的获奖工作－－激光冷却与捕陷原子的方法，其中主要有光学粘团、亚多普勒冷却、亚反冲冷却、激光原子阱等，叙述了它们的物理原理、重要意义及其应用。     

非球面检测中最佳入射球面波和最佳参考球面波的确定

为了能够对非球面光学元件面型进行高精度的干涉检测,提出了一种确定最佳入射球面波和最佳参考球面波的新方法。该方法通过计算分析入射球面波与非球面反射波干涉条纹密度,确定最佳入射球面波的波源位置;通过计算分析在干涉图记录平面CCD上干涉条纹的密度,确定非球面检测时参考球面波波源的最佳位置。应用该理论与方法,不仅可明确非球面检测时CCD等光路元件选型的具体策略,而且可用于指导非球面检测调试过程,并能够通过对干涉图的深入分析,获得更多被测非球面的信息。     

一维σ~+-σ~-冷却光和再抽运光对一维磁光陷阱中的多能级钠原子作用的研究

表述了钠Ｄ２线跃迁所包含的２４个磁子能级的原子在一维σ＋－σ－冷却光和再抽运光中产生的稳态多普勒冷却力。讨论了不同磁场强度、不同再抽运光强和失谐情况下原子的多普勒冷却力及对磁光陷阱中最大捕陷速度、原子数目及温度的影响     

一维σ^＋～σ^—冷却光和再抽运光对一维磁光陷阱中的多能级钠原？…

表述了钠Ｄ２线跃迁包含的２４个磁子能级的原子在一维σ＾＋～σ＾－冷却光和再抽运光中产生的稳态多普勒冷却力，讨论了不同磁场强度，不同再抽动光强和失谐情况下原子的多普勒冷却力及对磁光陷阱中最大捕陷速度，原子数目及温度的影响。     

激光冷却和捕陷中性原子③

6 激光冷却和捕陷中性原子技术的应用 前面已经提到,激光冷却和捕获中性原子技术最主要的应用是在精密计量和超冷原子物理两个方面.在精密计量方面最为典型的是可用于原子频标的"原子喷泉"(atomic fountain)技术;而在超冷原子物理方面最为典型的是玻色-爱因斯坦凝聚(Bose-Einstein condensation)和原子波激射器(atom laser)的实现.     

原子的激光冷却与捕陷(I)

本文综述了近年来原子的檄光冷却与捕陷领域实验工作的进展,首先介绍了辐射场对原子机械力作用的物理原理。然后分别叙述原子束的激光减速、原子束的激光准直、光学粘团（ｏｐｔｉｃａｌｍｏｌａｓｓｅｓ）和激光原子阱研究的成就．     

轴对称指向性球面波的界面反射波

无限大平面刚性障板中圆形活塞源的声辐射场可近似为轴对称指向性球面波,前人只给出了活塞面与界面平行时轴对称指向性球面波的界面响应表达式,本文针对活塞面与界面不平行的情况,推导了轴对称指向性球面波的锥面波展开式,并进一步导出了其界面反射波的表达式.在源距远大于声波波长的情况下通过鞍点法将界面反射波的表达式化简为了简化表达式.简化式不仅计算上简洁,而且物理含义清楚:轴对称指向性球面波的界面反射波可视为镜像活塞源激发的轴对称指向性球面波与反射系数的乘积.计算表明,当活塞半径小于声波波长时,反射波对活塞与界面的夹角和接收点的环向方位角不太敏感,反射波的指向性较弱;当活塞半径大于声波波长时,反射波对活塞与界面的夹角和接收点的环向方位角很敏感,反射波的指向性很强.增加活塞与界面的夹角,反射波先增加后减小,反射波的指向性先增强后减弱;当活塞与界面的夹角等于活塞中心镜像点与接收点的连线与界面法线的夹角时,反射波最大,反射波的指向性最强.     

Dynamics of moving interacting atoms in a laser radiation field and optical size resonances

The forces acting on interacting moving atoms exposed to resonant laser radiation are calculated. It is shown that the forces acting on the atoms include the radiation pressure forces as well as the external and internal bias forces. The dependences of the forces on the atomic spacing, polarization, and laser radiation frequency are given. It is found that the internal bias force associated with the interaction of atomic dipoles via the reemitted field may play an important role in the dynamics of dense atomic ensembles in a light field. It is shown that optical size resonances appear in the system of interacting atoms at frequencies differing substantially from transition frequencies in the spectrum of atoms. It is noted that optical size resonances as well as the Doppler frequency shift in the spectrum of interacting atoms play a significant role in the processes of laser-radiation-controlled motion of the atoms.     

Laser cooling of antihydrogen

We present a short review of the essential techniques of cooling free atoms by resonant laser radiation. The different contributions to the light forces are explained and their application to the problem of damping the thermal motion of free atoms is described. Due to quantum mechanical fluctuations of the light force there exists a limit temperature for a given atomic transition. Deceleration of atomic beams by the radiation pressure demands techniques to maintain the resonance condition while the Doppler shift of the decelerated atom is rapidly changing. Radiation forces may serve to compress and deflect slow atomic beams as well as to trap cold atoms. The possible use of pulsed laser radiation is discussed.     

Scattering of atoms by light

This review discusses the latest theoretical and experimental achievements in the resonant light pressure acting on the translational motion of atoms. Alongside with the effects due to the spontaneous light pressure (atomic deflection, velocity bunching, cooling), various manifestations of the effects of induced light pressure are considered in detail. This paper provides the theory and experiments of atoms scattering by a standing light wave under the conditions of coherent and non-coherent interaction, diffraction and interference of atomic beams. The problems where atomic motion along two trajectories and Landau-Zener transitions between them are essential, are studied. The kinetic phenomena (scattering, cooling, channeling) due to the motion of the particles exposed to gradient force and also friction and diffusion caused by spontaneous emission are considered. The influence of the recoil effect under spontaneous emission of atoms on non-linear polarization phenomena is discussed.     

双色激光场对运动原子的辐射压力

本文研究了双色行波场对运动原子的辐射压力，通过数值计算，分别得到了在不同光强，不同频率，不同传播方向条件下，原子在双色场中的受激跃迁速率和辐射压力随速度变化的关系。结果表明：双色场对原子的辐射压力和行波场及驻波场相比，有着许多不同特点，这些特点可以在激光冷却中性原子，原子速度选择，原子动量扩散的研究中加以利用。     

Modification of radiation pressure due to cooperative scattering of light

Cooperative spontaneous emission of a single photon from a cloud of N atoms modifies substantially the radiation pressure exerted by a far-detuned laser beam exciting the atoms. On one hand, the force induced by photon absorption depends on the collective decay rate of the excited atomic state. On the other hand, directional spontaneous emission counteracts the recoil induced by the absorption. We derive an analytical expression for the radiation pressure in steady-state. For a smooth extended atomic distribution we show that the radiation pressure depends on the atom number via cooperative scattering and that, for certain atom numbers, it can be suppressed or enhanced. Cooperative scattering of light by extended atomic clouds can become important in the presence of quasi-resonant light and could be addressed in many cold atoms experiments.     

Analysis of radiation pressure exerted on a metallic particle within an evanescent field

Radiation pressure induced by an evanescent field was experimentally analyzed for a single submicrometer-sized gold particle. The force measurement was based on a thermodynamic analysis of Brownian motion by use of a three-dimensional position-sensing technique. The lateral radiation pressure could be ascribed to a scattering force, which was oriented in the same direction as the propagation vector of the incident laser beam. The potential profile in the longitudinal direction indicated that the gold particle was attracted to the high-intensity region of the evanescent field by a gradient force.     

Feedback-controlled nonresonant laser cooling

We present a new approach to nonresonant laser deceleration and cooling of atoms based on their interaction with a bistable optical cavity. The cooling mechanism presents a photonic version of Sisyphus cooling, in which the conservative motion of atoms is interrupted by sudden transitions between two stable states of the cavity mode. The mechanical energy is extracted due to the hysteretic nature of those transitions. The bistable character of the cavity may be achieved by an external feedback loop, or by means of nonlinear intracavity optical elements. In contrast to the conventional cavity cooling, in which atoms experience a viscoustype force, bistable cavity cooling imitates “dry friction” and stops atoms much faster. Based on this novel approach, we explore the prospects of using optical bistability for efficient radiation pressure cooling of micromechanical devices that are modeled as a Fabry-Perot resonator with one fixed and one oscillating mirror. In all cases, analytical results are presented, supported by realistic numerical examples.     

Noninvasive generation and measurement of propagating waves in arterial walls

Arterial wall stiffness can be associated with various diseases. Arteriosclerosis involves the buildup of plaques within artery walls that stiffen the arteries. The stiffness of an artery can be assessed by measurement of the pulse wave velocity (PWV). Usually, PWV is estimated using the foot-to-foot method. However, the foot of the pressure wave is not very clear due to reflected waves. Also, the blood pressure wave generated by the heart is normally a low frequency wave, hence the time resolution is low. PWV is an average indicator of artery stiffness between the two measuring positions, and therefore cannot easily identify local stiffness. In this paper a force on the arterial wall is generated noninvasively by the radiation force of ultrasound. Techniques for measuring the propagating wave due to this localized force are studied. The excitation force can be either a very short pulse or a modulated cw signal of a few hundred hertz. The temporal resolution of this method, which is in the range of microseconds, is much higher than the conventional pressure PWV method, and therefore allows the wave velocity to be measured accurately over short distances of a few millimeters.     

激光驻波场形成Cr原子沉积纳米光栅的初步实验研究

利用激光驻波场会聚原子沉积纳米结构的技术可以用来研制纳米结构长度传递标准.当激光驻波场的频率大于原子的共振频率时，原子由于受到偶极力的作用将被会聚到驻波的波节处.采用了一种新的技术方案减小了实验对大的激光功率的要求.利用激光驻波场会聚准直性较好的Cr原子，并使其沉积在硅基片上形成纳米光栅结构.经原子力显微镜测试表明纳米光栅的周期为215 nm. 关键词： 激光偶极力 纳米计量 原子沉积 蓝失谐     

Effect of quantum interference processes on the angular distribution of the spontaneous radiation in the D line of alkali-metal vapors in a laser wave field

The resonance fluorescence of a degenerate V-type three-level atom in the field of an intense monochromatic wave with arbitrary polarization composition is investigated. The equations of motion, the general form of the radiation relaxation operator, and the analytical expressions for the angular distribution of the intensity of the spontaneous radiation from atoms, and the total intensity of the resonance fluorescence for such systems are obtained. The angular distribution of the spontaneous radiation from atoms for the D line of alkali-metal vapors is investigated. It is predicted theoretically that the intensity of the resonance fluorescence will decrease as the intensity of the pump wave increases in observations in a direction of the electric field vector of the laser wave.