双高A档院校2019年科研成果分析:基于CNKI的数据

基于CNKI数据库中10所双高A档院校2019年的学术论文、科研课题和专利等科研成果数据,采用文献计量软件进行文献计量及可视化分析,双高A档院校在高职教育科研工作中的示范作用,引领其他高职院校服务国家战略,促进与行业领先企业深度融合,逐步形成校企命运共同体,在新时代中国特色高职教育科研征途上谱写新篇章.     

Production of 87Rb Bose-Einstein condensates in a hybrid trap

We report a rapid evaporative cooling method using a hybrid trap which is composed of a quadrupole magnetic trap and a one-beam optical dipole trap. It contains two kinds of evaporative coolings to reach the quantum degeneracy: initial radio-frequency (RF) enforced evaporative cooling in the quadrupole magnetic trap and further runaway evaporative cooling in the optical dipole trap. The hybrid trap does not require a very high power laser such as that in the traditional pure optical trap, but still has a deep trap depth and a large trap volume, and has better optical access than the normal magnetic trap like the quadrupole-Ioffe-configuration (QUIC) cloverleaf trap. A high trap frequency can be easily realized in the hybrid trap to enhance the elastic collision rate and shorten the evaporative cooling time. In our experiment, pure Bose-Einstein condensates (BECs) with about 1 × 105 atoms can be realized in 6 s evaporative cooling in the optical dipole trap.     

正在崛起的新兴节能产业

随着全国24个省市先后出现“电荒”,节约能源已成为全社会关注的热点。但在市场经济环境中,如何有效地节能降耗,仍是有待破解的难题。记者最近在京、鲁、鄂、渝等省市了解到,一种基于市场化运作、由节能公司承担主要节能风险的节能新机制——EMCO,正在北京、山东、辽宁等省市试点,全国已有100多家企业参与了这一新节能模式。业内人士认为,随着全社会对节能的高度重视,EMCO正在成为新兴的节能产业。     

Optimization of temperature characteristics of a transportable ~(87)Rb atomic fountain clock

A high-performance transportable fountain clock is attractive for use in laboratories with high-precision time-frequency measurement requirements. This Letter reports the improvement of the stability of a transportable rubidium-87 fountain clock because of an optimization of temperature characteristics. This clock integrates its physical packaging, optical benches, microwave frequency synthesizers, and electronic controls onto an easily movable wheeled plate. Two optical benches with a high-vibration resistance are realized in this work. No additional adjustment is required after moving them several times. The Allan deviation of the fountain clock frequency was measured by comparing it with that of the hydrogen maser. The fountain clock got a short-term stability of 2.3 × 10~(-13) at 1 s and long-term stability on the order of 10~(-16) at 100,000 s.     

Loss of cold atoms due to collisions with residual gases in free flight in a magneto-optical trap

The loss rate of cold atoms in a trap due to residual gas collisions differs from that in a free state after the cold atoms are released from the trap. In this paper, the loss rate in a cold rubidium-87 atom cloud was measured in a magneto-optical trap(MOT) and during its free flight. The residual gas pressure was analyzed by a residual gas analyzer, and the pressure distribution in a vacuum chamber was numerically calculated by the angular coefficient method. The decay factor, which describes the decay behavior of cold atoms due to residual gas collisions during a free flight, was calculated. It was found that the decay factor agrees well with theoretical predictions under various vacuum conditions.     

基于光纤激光放大倍频的冷原子钟光源

用于激光冷却与原子布居数探测的激光光源是冷原子钟的重要组成部分,选用工业技术成熟的1560 nm光纤激光器和光纤放大器分别作为种子源和光放大器,经非线性倍频晶体对放大后的激光进行倍频,得到较大功率的780 nm的激光,通过饱和吸收稳频得到冷却激光,一部分冷却激光利用电光调制器和声光调制器移频6.8 GHz得到重泵浦激光,对上述激光进行适当的功率分配后提供给冷原子钟。对该套激光装置关键器件进行了特性测试,将稳频后的倍频激光与锁定在超稳激光上的光学频率梳进行拍频,得到的激光的线宽在74 kHz左右,其短期稳定度比外腔半导体激光器提高半个多数量级。将这样的激光光源应用于冷原子钟,可以减小探测激光频率噪声对喷泉钟稳定度的限制。