微重力环境下冷原子物理及其应用

文章介绍了国际上微重力环境下冷原子物理及其应用的研究工作：空间原子钟、原子干涉仪、超冷原子物理和建议中的广义相对论的探索。文中简要介绍了中国科学院上海光学精密机械研究所在微重力环境下所进行的空间原子钟、玻色-爱因斯坦凝聚和原子芯片等研究工作。     

Proposal of a Novel Compact Cold Atomic Fountain Clock

We propose a novel atomic fountain clock which is compact and transportable. The clock is 60-cm in height. Its linewidth is expected to be 1.75Hz, with accuracy 10^-14, stability 10^-14 and signal-noise ratio 10^3. A hollow beam is applied as atomic wave-guide, which can increase the stability and the signal-noise ratio by one order. The hollow beam will not affect the accuracy of the clock, if the frequency shift due to the hollow beam is amended and the fluctuation of the hollow beam intensity is controlled to be smaller than 0.6%.     

Fold optics path: an improvement for an atomic fountain

A fold optical path is utilized to capture and launch atoms in the atomic fountain.This improved technique reduces the laser power needed by 60 percent,facilitates suppression of the laser power fluctuations,and leads to a more simple and stable system.     

Progress of the 87Rb Fountain Clock

A fountain atomic clock based on cold 87Rb atoms has been in operation in our laboratory for several months. We therefore report the design of the rubidium fountain clock including its physical package, optical system and daily operation. Ramsey fringes have been attained with the signal to noise ratio of about 100.     

Proposal of a dual-ball atomic fountain clock

A simple improved structure is designed to trap and launch two cold atomic balls vertically at the same time,which works like"two fountains",but is more compact since most components of the"two fountains" are shared.It is expected to improve the stability of the fountain markedly.     

原子喷泉频标:原理与发展

介绍了喷泉频标的原理与发展.喷泉频标是一项近20年来发展起来的原子钟技术,它以激光冷却技术为基础,利用该技术实现了冷原子介质的俘获与上抛.冷原子介质在上抛下落过程中首先完成原子态制备,然后两次通过微波谐振腔实现Ramsey作用,在两次作用之间原子经历自由演化,最后原子经过探测区,通过双能级荧光探测法探测原子跃迁概率得到鉴频的Ramsey干涉条纹,并实现频率锁定,其中心条纹的线宽在1Hz左右.频率稳定度和频率不确定度是喷泉频标的两个重要指标.影响喷泉钟频率稳定度的因素主要有量子投影噪声和电子学噪声,目前喷泉钟的短期稳定度为(10~(-13)—10~(-14))τ~(-1/2),长期稳定度在(10~(-16)—10~(-17))量级.喷泉频标的频率不确定度主要受二阶塞曼频移、黑体辐射频移、冷原子碰撞频移以及与微波相关的频移等的影响.目前喷泉钟的不确定度在小的10~(-16)量级.作为基准频标,喷泉钟的工作介质主要是~(133)Cs,~(87)Rb.国际各大计量机构都研制了喷泉频标,它在各地协调世界时的建立、国际原子时的校准等方面发挥着越来越重要的作用.此外,喷泉频标还用于研究高精度时频基准和时间比对链路、验证基本物理理论等.     

Chaotifying a linear time-invariant system by the state feedback controller and sawtooth function

Another algorithm for chaotification of any given linear time-invariant discrete-time systems is presented. The new chaotification algorithm uses the decentralized control and the continuous sawtooth function, which can generate discrete chaos with an arbitrarily desired amplitude bound. Based on the Marotto theorem, we mathematically prove that the controlled system is chaotic in the sense of Li and Yorke. Finally, a simple example is used to illustrate the effectiveness of the proposed theory and method.     

机电类专业高等数学的应用性教学改革的实践

重点介绍了在机电学院如何展开高等数学的应用性教学改革,并在现有教学条件下做了改革实验,取得了较好的改革效果.但最为重要的是本文提出了一种新的高等数学的改革思路.     

Observation of Modulation Transfer Spectroscopy in the Deep Modulation Regime

We observe the modulation transfer spectroscopy on the D2 line of ^87Rb in a rubidium cell with acoustic-optic modulator in the deep modulation regime. In this regime, the sidebands of the pump beam are involved in the four-wave mixing processes, which increase the signal gradients and the peak-to-peak amplitudes of both the absorption and dispersion components.     

Magnetic field measurement on ~(87)Rb atomic fountain clock

<正>An experiment on measuring the magnetic field in Ramsey interaction region of the atomic fountain clock by detecting the Zeeman frequency shift of ~(87)Rb hyperfine transition is presented.By mu-metal shielding and coils compensating,the magnetic fluctuations resulting from asymmetry and instability are less than 10 and 0.025 nT,respectively.The relative frequency uncertainty of atomic fountain clock caused by the magnetic field is less than 5.4×10~(-16).