脉管制冷与气波制冷耦合的研究

介绍了一种耦合脉管制冷与气波制冷技术的新型制冷机脉管式气波制冷机。分析了脉管式气波制冷机的制冷原理 ,对脉管制冷与气波制冷的耦合性进行了试验研究。同时 ,对振荡管长度、气体分配器的转速等影响脉管式气波制冷机性能的因素进行了试验。通过研究 ,获得了一些有益的结论 ,并给出了各种因素对制冷机等熵效率的影响曲线     

High performance of semiconductor optical amplifier available for cold atom physics research

We present a novel design of a compact, stable, and easy-adjustable semiconductor optical amplifier （SOA） system. This SOA system is capable of providing up to 560-roW laser power at the wavelength of 852 nm. For the continuous-wave （CW） seeding laser, the amplification gain can reach 18 dB. We add amplitude modulation onto the CW laser and measure the modulation amplification between seeding and output laser. The amplification gain remains constant within the frequency range from 10 Hz to 1 MHz. The whole system could work in ultra-stable condition： for CW seeding laser, the fluctuation of output power is less than 0.33% in several hours.     

北京大学玻色-爱因斯坦凝聚的实现及研究进展

在这里我们报道北京大学玻色-爱因斯坦凝聚的实现和研究进展.观察到单个和多个组分的87 Rb玻色-爱因斯坦凝聚的形成.介绍了北京大学玻色-爱因斯坦凝聚的实验系统,包括达到10-11毫巴的双磁光阱超高真空系统,大功率半导体激光系统,激光稳频和频率控制系统, QUIC磁阱及磁阱的控制系统,蒸发冷却系统,吸收成像和CCD数据采集处理系统,LabVIEW时序控制系统.     

自相似分量过程Hausdorff维数结果

设Ｘ（ｔ）（ｔ∈Ｒ＋）是一个具有独立自相似分量过程。我们在一些较弱的条件下得到了它的像集和图订的Ｈａｕｓｄｏｒｆｆ维数。     

High Field Seeking State Atom Laser and Properties of Flux

We present an experimental study on the continuous atom laser. The experiments show that a high field seeking state atom laser with stable flux can be formed by increasing the strength of outcoupling before large density fluctuations appear. It is easy to obtain a long length or high speed output with this kind of atom laser.     

用吸收成像法分析玻色-爱因斯坦凝聚的逃逸蒸发冷却

本文介绍利用吸收成像法得到的光学厚度来作为是否进行有效蒸发冷却的判据的基本原理.利用蒸发冷却实现BEC的过程中,过快或过慢的降低磁阱深度,都会带来大量的原子数损失和低的蒸发冷却效率.蒸发冷却过程必须是一个满足逃逸蒸发冷却(runaway evaporation)条件的有效的过程.利用光学厚度和弹性碰撞率之间的关系,可直接用吸收成像法分析蒸发冷却过程是否有效.文中还结合北京大学量子信息与测量实验室实现BEC的实验数据加以说明.     

算子自相似马氏过程的Hausdorff维数定理

对各向同性,算子自相似马氏过程,本文在恰当的条件下得到了其象集与图集的Ｈａｕｓｄｏｒｆｆ维数。其证明表明该维数的估计与其算子特征值的实部有关。     

玻色-爱因斯坦凝聚研究的过去与未来

 2001 年,瑞典皇家科学院宣布2001 年诺贝尔物理学奖分别授予美国科学家埃里克·康奈尔（Eric Cornell）、德国科学家沃尔夫冈·克特勒（Wolfgang Ketterle）,以及美国科学家卡尔·韦曼（Carl Wieman）。     

Stabilized DFB laser system with large tuning range

We propose, design, and realize a compact stabilized laser system that can be tuned within 24 GHz automatically.This laser system consists of two distributed feedback(DFB) lasers, one of which is reference and locked to the D2 line of ~(87)Rb, the other laser is a slave that is locked to the reference laser via a loop servo. We measured the frequency of the beating signal of the two lasers and generated an error signal, which controlled the frequency of the slave laser to close the loop. We compressed the fluctuation of the beating signal's frequency to less than 1 MHz.Furthermore, the system can also automatically determine and control whether the slave is red detuned or blue detuned to the reference. The dimensions of our laser system are about 15 cm × 20 cm × 10 cm. This kind of laser system can be applied in many important applications, such as atomic interferometer and cold atomic clock.