芯片原子钟研究进展
文献类型：学位论文
| 作者 | 程峰 |
| 学位类别 | 博士 |
| 答辩日期 | 2012 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 王育竹 |
| 关键词 | 原子钟 原子芯片 玻色-爱因斯坦凝聚 电磁感应透明 |
| 其他题名 | Progress of trapped atom clock on a chip |
| 中文摘要 | 本论文介绍了我在铷87芯片原子钟方面进行的理论与实验工作。 在这篇论文中，我提出了两种光抽运方法来进行初态制备。这两种方法可以增加芯片原子钟的原子数。本论文还对芯片原子钟的频移、退相干以及噪声进行了讨论。我使用一个简单的模型解释了增加碰撞频移可以抑制退相干的原因。在实验方面，我们搭建了一个超高真空系统用来实现各项原子冷却与囚禁技术。利用外部反亥姆霍兹线圈以及原子芯片上的镜面，我们成功的从背景真空中捕获到大约2×10^7个原子。之后通过偏振梯度冷却将原子温度冷却至20μK。我们还将原子抽运到弱场寻找态并将原子囚禁在原子芯片产生的磁阱中。通过射频蒸发冷却继续冷却原子的温度，直至原子团相变成玻色-爱因斯坦凝聚（Bose-Einstein condensation，BEC）。此外我们还使用法拉第旋光效应来探测冷原子，探测结果与其他探测手段的得到的结果基本一致，而且对比度和信噪比相对传统的荧光法和吸收法都有所提高。 本论文的另一项内容介绍了我们在原子芯片上实现电磁感应透明（electromagnetically induced transparency，EIT）的工作，这是脉冲相干存储（pulsed coherent storage，PCS）原子钟的前期工作。我们制备了信号光和控制光并让它们通过一团冷原子。通过固定控制光的频率并扫描信号光的频率，我们发现在双光子共振点附近信号光的吸收谱线有明显透明窗口。谱线宽度大约为100KHz，最高透明度达到98%。 |
| 英文摘要 | This thesis presents my work on theory and experiments of Rb 87 trapped atom clock on a chip (TACC). In this thesis, I proposed two methods for initial state preparation by optical pumping which could increase atom number of TACC. Its frequency shifts, decoherence and noises were also discussed. I used a simple model to show that decoherence could be suppressed by increasing collision shift of atoms. In experiments, we built an ultrahigh vacuum system to realize different methods atom cooling and trapping. Pulsed switching dispenser and light induced atom disorption technique were used to change vacuum degree rapidly. By using a pair of external anti-Helmhltz coils and mirror on the chip, we captured almost 2×10^7 atoms from background vapor. Then they were further cooled by molasses to a temperature about 20μK. We also pumped the atoms to a weak-field seeking state and trapped them in a magnetic trap created by the atom chip. They were further cooled in the trap by radio-frequency evaporative cooling until Bose-Einstein condensation appears. We also demonstrated that the Faraday effect can be used to detect cold atoms. The result of detection was almost same with other methods but the contrast and signal to noise ratio were much higher than absorption and fluorescence detection. Another part of this thesis exhibits the realization of electromagnetically induced transparency on atom chip which is the prior work of pulsed coherent storage atomic clock. We illuminated an atom cloud by signal light and control light. By scanning the frequency of signal light while fixed that of control light, we observed a transparency window in the absorption spectrum of signal light. The linewidth of the window was about 100KHz with the maximum transparence almost 98%. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15700]  |
| 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 | 程峰. 芯片原子钟研究进展[D]. 中国科学院上海光学精密机械研究所. 2012. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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