用于原子干涉仪实验的锂原子的塞曼减速与磁光囚禁

为了制备适于原子干涉仪实验的低温锂原子样品,开展了锂原子的塞曼减速及与磁光阱囚禁相关的实验研究.设计并实现了一种结构紧凑的腔体内冷式多级线圈叠加的塞曼减速器,将速度小于600 m/s的7Li原子减速到60 m/s,磁光阱装载速率为5×108/s,囚禁原子数目1×109个,原子团的最低温度约为220±30μK.研究了光学黏胶中7Li原子的寿命与囚禁光频率失谐量的关系.这些结果为进一步开展7Li原子亚多普勒冷却、光势阱蒸发冷却以及原子干涉仪实验奠定了基础.     

原子干涉仪和原子光学研究的最新进展

综述了近年来原子干涉仪和原子光学研究领域研究领域工作的最近进展。重点介绍了德布罗意原子物质波干涉仪的基本物理原理，原子的杨氏双缝干涉实验，利用受激拉曼跃迁的原子干涉仪和Ｒａｍｓｅｙ原子干涉仪。     

基于1560 nm外腔式激光器的拉曼光锁相技术

拉曼光产生技术是量子精密测量领域的一个重要研究内容,是冷原子重力仪、冷原子陀螺仪等量子惯性传感器的关键技术.对于铷87原子,需要两束频差6.834 GHz且相位稳定的780 nm激光来产生拉曼光.基于两台外腔式780 nm激光器,并利用光学锁相环技术可以产生拉曼光,但系统复杂、环境适应性不强.基于内腔式1560 nm激...     

光和原子关联与量子计量

物理量的测量与单位标准的统一推动了计量学的发展.量子力学的建立,激光技术的发明以及原子与分子物理学的发展,在原理与技术上进一步刷新了计量学的研究内涵,特别是激光干涉与原子频标技术的发展,引起了计量学革命性的飞跃.基于激光干涉的引力波测量、激光陀螺仪,基于原子干涉的原子钟、原子陀螺仪等精密测量技术相继诞生,一个以量子物理为基础,探索与开拓物理量精密测量方法与技术的新的科学分支——量子计量学(Quantum Metrology)已然兴起.干涉是计量学中最常用的相位测量方法.量子干涉技术,其相位测量精度能够突破标准量子极限的限制,是量子计量学与量子测量技术的核心研究内容.本文重点介绍近几年我们在量子干涉方面所取得的新开拓与新发展,主要内容包括基于原子系综中四波混频过程的SU(1,1)型光量子关联干涉仪和基于原子系综中拉曼散射过程的光-原子混合干涉仪.     

多普勒型原子干涉仪的理论探讨

通过分析运动三能级原子与驻波激光场的斜交相互作用，设计了两种原子干涉仪．通过对原子波在这两种干涉仪中分裂、偏转和重合等全过程的分析，证明当原子和光场满足一定条件时，原子不同内态间的干涉效应将产生．最后对利用这两种方法实现和观察原子波的干涉在理论上作了一些探讨 关键词：     

冷原子干涉仪及空间应用

原子干涉仪是利用原子物质波的特性而实现的干涉仪,冷原子具有很小的速度和速度分布以及良好的相干性,因而冷原子干涉仪具有很高的灵敏度.文章介绍了原子干涉仪的基本物理原理、国内外研究进展、原子干涉仪实现方案及其在精密测量和空间科学领域中的应用.     

冷原子干涉仪及空间应用

原子干涉仪是利用原子物质波的特性而实现的干涉仪,冷原子具有很小的速度和速度分布以及良好的相干性,因而冷原子干涉仪具有很高的灵敏度.文章介绍了原子干涉仪的基本物理原理、国内外研究进展、原子干涉仪实现方案及其在精密测量和空间科学领域中的应用.     

分析原子干涉仪的矩阵方法

从原子波包所满足的薛定谔方程出发,从理论上巧妙地推导出了原子干涉仪在重力的影响下所产生的相位差与重力加速度的关系表达式。提出了一种3×3阶的矩阵方法,以此来分析多个元件情况下原子干涉仪中的相位差,可以大大简化计算。利用这种方法不但能得到原子束在重力的影响下在自由空间中的传输矩阵,也可以得到原子束与π/2和π脉冲的相互作用矩阵。作为例子,用3×3阶矩阵方法计算了三脉冲原子干涉仪中的相位差,得出的结果与Wolf等对经典轨迹进行拉格朗日积分所得出的结果完全相符。进一步分析了五脉冲的原子干涉仪中的相位差,以说明3×3阶矩阵方法的简便性。     

不同序列拉曼光脉冲对原子重力仪灵敏度的影响

研究了不同序列拉曼光脉冲对原子重力仪灵敏度的影响.结果表明,通过调节脉冲间隔可以改善原子干涉重力仪的灵敏度.在标准配置下,只考虑重力及一阶重力梯度时,三脉冲序列（π/2-π-π/2）的原子干涉重力仪具有较大的灵敏度,四脉冲序列（π/2-π-π-π/2）的原子干涉重力仪对重力不敏感,可用来测量重力梯度,五脉冲作用会降低原子干涉重力仪的灵敏度. 关键词： 原子重力仪 拉曼激光脉冲序列 灵敏度     

冷原子物质波干涉仪的应用

原子干涉仪可以获得比传统光学干涉仪更复杂的干涉信息,冷原子具有很小的速度及速度分布,拥有足够长的相干时间,使得基于冷原子干涉仪的测量仪器具有很高的灵敏度,被广泛应用于精密测量领域。自利用脉冲激光的拉曼干涉仪搭建成功后,随着冷原子相关操控技术的发展成熟,基于冷原子干涉仪的重力仪、重力梯度仪都取得了一定的进展,本文综合了近年来国内外相关文献成果并给出了总结与思考。     

非简并拉曼过程中交流斯塔克位移对原子反转的影响

利用修正后的有效哈密顿量计算非简拉曼过程中原子反转的演化，并研究交流斯塔克位移对拉比振荡崩溃和再生的影响。结果发现：交流斯克位移的存在使得非简并拉曼过程中原子反转的崩溃与再生现象呈现较好的周期性，并且拉比振荡的频率和幅均受交流斯塔克位移的影响。     

Effective Raman Theory for a Three-Level Atom in the V-Configuration

It is shown that the system of a three-level atom coupled with two modes of quantized cavity fields in the V-configuration with arbitrary detunings can be exactly reduced to a two-level system with a nonsingular effective coupling which depends nonlinearly on the intensity of the two cavity fields. By performing a unitary transformation, we obtain an exact transformed Hamiltonian in which one of the three levels is decoupled for all values of the detunings including the zero-detuning. We also present the analytical expressions of energy eigenvdues and eigenvectors, evolution operator, time-varying atomic inversion operator and photon number operators of the two modes for the effective two-level model.     

Wavelength-Tunable Laser-Diode Interferometer

Laser diodes (LDs) have been applied to a phase-measuring interferometer through the wavelength tunability of LDs by controlling their currents. Laser-diode interferometers based on a heterodyne technique are reviewed. A two-wavelength laser-diode interferometer is demonstrated with current control of dual LDs in opposite directions. A synthetic wavelength makes it possible to extend the range of interferometric measurements. The wavelength is controlled by the laser injection current and is stepwise or rampwise changed to introduce a time-varying phase difference between the two beams of an interferometer with unbalanced optical path lengths. The optical output is demodulated with a phase-extraction algorithm. Systematic phase errors caused by the LD-power variation and by the difference between the beat frequency and ramp frequency are analyzed. A feedback interferometer with electronics is used to eliminate the phase error by locking the interferometer on a preset phase. Typical experimental results are shown.     

Demonstration of a Sagnac-Type Cold Atom Interferometer with Stimulated Raman Transitions

Cbld-matter-wave Sagnac interferometers possess many advantages over their thermal atomic beam counterparts when they are used as precise inertial sensors. We report a realization of a Sagnac-type interferometer with cold atoms. Cold rubidium atoms are prepared in a magneto-optical trap and are pushed by resonant laser pulse to form slow atomic beam. In the interference region, atomic wave packets are coherently manipulated using π/2 -π - π/2 Raman pulse sequences. Interference fringes with maximum contrast of 37% are observed experimentally.     

聚合物分散液晶的制备及拉曼光谱分析

用溶致相分离的方法制备了以PMMA为基体的四种不同配比的聚合物分散液晶(PDLC),四氢呋喃为引发剂,并且通过傅立叶拉曼光谱仪对其进行检测,分析其光谱,观察各单体混合前后性质的变化,鉴别聚合物分散液晶的物质构成。此外,在指定的组分前提下,根据液晶最强峰与PMMA特征峰的相对强度拟合曲线得出PDLC中液晶与PMMA的质量百分比,为下一步研究聚合物分散液晶系统的光折变特性提供指导。     

Phase Measurement Algorithm in Wavelength Scanned Fizeau Interferometer

Wavelength scanned interferometry allows the simultaneous measurement of top surface shape and optical thickness variation of a transparent object consisting of several parallel surfaces. Interference signals from these surfaces can be separated in frequency space, and their phases are detected by discrete Fourier analysis. However, these signal frequencies are shifted from the detection frequency by the refractive index dispersion of the object and a nonlinearity of the wavelength scanning. The Fourier analysis is sensitive to the detuning of the signal frequency and suffers from the multiple-beam interference noise. Conventional error-compensating algorithms cannot be applied to an object consisting of more than three reflecting surfaces. We derive a new 2N-1 sample error-compensating algorithm, which allows the phase detection of any order of harmonic frequency among the interference signals. The new algorithm suppresses the effect of signal frequency detuning as well as the multiple-beam interference noise and can be applied to the measurement of complex objects consisting of more than three reflecting surfaces.     

傅里叶变换干涉仪激光信号处理电路的分析

激光信号处理电路是傅里叶变换干涉仪的重要组成部分,为提高干涉仪控制器的控制精度,在分析干涉仪工作特点的基础上设计了激光信号处理电路,并着重分析了四阶Besell带通滤波器的误差传递路径,及各噪声对信号质量的影响,从而为低噪声电路设计提供一定的理论基础,具有参考作用.最后,半实物仿真结果表明所设计的激光信号处理电路精度达到0.01％,从而验证了所设计电路的合理性.     

Noncontact Measurement of Surface Topography by Mirau Interferometer

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Tunable Polycyclic Chiral Beams

The generation of polycyclic chiral beams by inducing annular spiral zone phases that consist of multiple subphases is numerically and experimentally demonstrated. Each subphase is composed of a spiral phase, an equiphase, and a radial phase. The number and twisting direction of the spiral intensity lobes for every layer could be individually controlled. Furthermore, the orientations for the twisting lobes could be tuned by changing the introduced equiphase gradient. More importantly, such optical fields also show rotation property when the equiphases with gradient are dynamically and continuously imposed. This advantage of rotation also brings about the possibility of such chiral beams to rotate particles. Such beams would be advantageous for manufacturing tunable chiral metamaterials and have potential applications in optical tweezers and optical communication.