| 题名 | 中性汞原子磁光阱装载率的优化 |
| 作者 | 苟维 |
| 学位类别 | 硕士 |
| 答辩日期 | 2016 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 徐震 |
| 关键词 | 汞原子 光晶格钟 激光冷却 磁光阱 |
| 其他题名 | Optimization of the loading rate of mageto-optical trap for neutral mercury atom |
| 中文摘要 | 光晶格钟是当前计量科学研究中的热点。汞原子由于具有钟频跃迁受黑体辐射频移影响较小，核电荷数大，质量大等特点，成为下一代光晶格钟的热门候选。要实现汞原子光晶格钟，首先要利用1S0-3P1跃迁在磁光阱中对汞原子进行激光冷却和囚禁。提高磁光阱装载率，可以增加光晶格中的冷原子数目，从而降低量子投影噪声极限，提高光晶格钟性能。作者在攻读硕士学位期间从理论计算和实验比较两个方面，研究了三维磁光阱和二维磁光阱中的原子运动，来提高磁光阱装载率。 首先，计算了单腔磁光阱中汞原子感受到的光的散射力，分析了原子的一维运动规律，获得了特定参数下的磁光阱的最大俘获速率。在一维计算的基础上，使用随机数方法计算了三维磁光阱中的装载率。由于装载率和磁光阱中冷原子数目成正比，可以用实验测量结果和理论计算进行比较。通过已有实验系统上的测量，校准了磁光阱真空腔中的汞原子背景蒸汽压，并测量了稳态原子数。通过理论计算和实验探索了冷却激光的光强、冷却激光失谐量和磁光阱的磁场梯度对于稳态原子数的影响，获得了汞原子激光冷却最佳参数。计算结果和实验数据基本符合。 其次，通过二维磁光阱来产生高强度冷原子束流，降低了磁光阱区域的背景真空度，也可以进一步提高磁光阱的装载率。作者分析了不同方案的二维磁光阱的特点，建立了二维磁光阱的理论模型。计算了二维磁光阱的束流强度，以及相关参数对二维磁光阱性能的影响。 这些计算结果和实验测量，为进一步提高汞原子光晶格钟的装载率,从而提升汞原子光晶格钟的性能，提供了重要的科学依据。对汞原子光晶格钟的研究，具有重要的应用价值。 |
| 英文摘要 | Optical lattice clock is a hot topic in the research of frequency standard and metrology. Neutral mercury atom is one of the most promising candidates for optical lattice clock. Due to its large atomic number, mercury atom is insensitive to black body radiation, which is the severe limitation for the development of optical lattice clocks. To realize the optical lattice clock for neutral mercury atoms, the first step is laser-cooling and trapping of neutral mercury atoms in the magneto-optical trap (MOT) with 1S0-3P1 transition. Increasing the loading rate of magneto-optical trap (MOT) can help increasing the atom number in the optical lattice, lowering the quantum projection noise and thus improving the performance of optical lattice clock. The author studied atomic motion in 3D-MOT and 2D-MOT through theoretical calculation, as well as experiment to improve the loading rate of the MOT. Firstly, the author calculated the scattering force of deep UV cooling laser, which exerts on mercury atom in our single chamber MOT, and numerically simulated the one dimensional motion of the atom in the 1D-MOT. It gives us the capture velocity under specified parameters of the MOT. Then we calculated the loading rate of 3D-MOT with a high efficient random sampling method. The loading rate of the MOT is proportional to the atom number of the steady state, so we can compare our calculation with experiment results. We also calibrate the vapor pressure of background mercury gas in the vacuum chamber, and measured the atom number in a steady MOT. By Numerical simulation and experimental measurement, we studied the influence on the steady atom number with the parameters of MOT, such as laser intensity, laser detuning and magnetic field gradient. And we found the optimized parameters of MOT to maximize the loading rate. The calculated results are agreed with the experimental results. Secondly, with 2D-MOT, we can generate high flux cold atomic beam to enhance the loading rate of the MOT, as well as decrease the background pressure. The author analyzed typical features of different scheme of 2D-MOT, constructed the theoretical model of 2D-MOT and calculated the flux of cold atomic beam from 2D-MOT, then studied the influence of relevant parameters on the performance of 2D-MOT. These calculations and experimental measurements lay a good foundation for the further improvement of the loading rate of the MOT as well as performance of the optical lattice clock. And they have important practical value for the research of optical lattice clock for neutral mercury atoms. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/17001]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 苟维. 中性汞原子磁光阱装载率的优化[D]. 中国科学院上海光学精密机械研究所. 2016. |
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