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题名	积分球冷原子钟噪声抑制实验研究
作者	王亚宁
文献子类	博士
导师	刘亮
关键词	激光冷却 Laser Cooling 积分球 Integrating Sphere 频率综合器 Frequency Synthesizer 光抽运 Optical Pumping 腔牵引效应 Cavity Pulling Effect 频率稳定度 Frequency Stability
其他题名	Experiment on noise suppression of the integrating sphere cold atom clock
英文摘要	本论文介绍了作者博士期间在积分球冷原子钟原理样机上进行的针对系统噪声抑制的实验研究工作。对于积分球冷原子钟，影响其短期稳定度的主要噪声源包括：本地振荡器相位噪声（Dick效应），原子散粒噪声和量子投影噪声，激光器频率及强度噪声和电子学噪声等。为了提高积分球冷原子钟的短期稳定度，首先考虑降低Dick效应对积分球冷原子钟频率稳定度的影响，为此我们搭建了适用于积分球冷原子钟的微波源系统，并测试新微波源的相位噪声，其在1 Hz频偏处相位噪声为-60 dBc/Hz，白相位噪声平台为-110 dBc/Hz，基本复制了晶体振荡器的噪声性能。将该微波源应用到积分球冷原子钟原理样机，经过计算，新微波源引起的Dick效应为2.0×10-13τ-1/2，相比之前的商用频率综合器，原子钟的短期稳定度从7.3×10-13τ-1/2提高至5.1×10-13τ-1/2。另外，我们还搭建了一套高分辨率、低噪声微波源，相比于之前直接反馈晶体振荡器的实验方案，我们将误差信号反馈到锁相环内的DDS，因此系统调谐分辨率可以提高两个数量级，该方案可以降低反馈电子学噪声。为了进一步提高原子钟的短期稳定度，我们采用了一种新的抽运方案，即光抽运和微波抽运结合的方法，该方案提高了冷原子在钟跃迁能级上的布居，从而降低了原子散粒噪声和量子投影噪声。利用该方案，积分球冷原子钟的短期稳定度达到了4.2×10-13τ-1/2，在积分时间为40 000 s时，原子钟频率稳定度达到了2.0×10-15。 原子钟的短期稳定度反映了系统的信噪比，而长期稳定度则反映了系统的稳定性。通过理论分析和实验研究，影响积分球冷原子钟长期稳定的因素主要包括：腔牵引效应，二阶塞曼频移，黑体辐射频移，冷原子碰撞频移等，并对其做定量分析。为了获得积分球冷原子钟的长期稳定度，我们采用与氢钟比对的方法，通过10天的连续闭环锁定测试，积分球冷原子钟稳定度为5.4×10-13τ-1/2（τ=1~ 10000s），在积分时间为200 000 s时，其频率稳定度达到了2.6×10-15。经过分析与测试表明，长期稳定度的主要限制因素为腔牵引效应，是由于环境温度起伏导致微波腔共振频率变化引起的。; This dissertation presents the works on the noise suppression of the principle prototype of the integrating sphere cold atom clock (ISCAC) developed in Shanghai institute of optics and fine mechanics during the author’s doctoral studies. It mainly focus on the improvement of the frequency stability by decreasing the noise that limit the short-term frequency stability of the ISCAC. The noise sources include: the phase noise of the local oscillator via the Dick effect, the atomic shot noise and quantum projection noise, laser frequency and intensity noise and the electronic noise etc. Firstly, we built the microwave synthesizer considering the time sequence of the ISCAC to decrease the impact of the Dick effect on the performance of the atomic clock. We measured the phase noise performance of the homemade microwave source. The phase noise of the output 6.834 GHz signal is -60 and -110 dBc/Hz at 1 Hz and 10 kHz fourier frequencies, respectively. This new microwave source with low phase noise was used as the local oscillator of the ISCAC. The limitation of the Dick effect was reduced to 2.0×10-13τ-1/2 and the the frequency stability was improved from 7.3×10-13τ-1/2 to 5.1×10-13τ-1/2. To further improve the short-term frequency stability of the ISCAC, we applied an optical-microwave pumping method to prepare more atoms in the state for clock transition. With this method, the short-term frequency stability of the ISCAC was improved to 4.2×10-13τ-1/2, and 2.0×10-15 was reached at the averaging time of 40 000 s. The improvement of the short-term frequency stability of the atomic clock means the suppression of the noise in the system, while the long-term frequency stability needs the strict control of the environment around the system. We theoretically analyzed the physical quantities which could induce the frequency shift of the clock transition and obtained their sensitivities. These physical effects mainly include: cavity pulling effect, the second-order Zeeman effect, blackbody radiation effect and collision effect etc. The physical quantities were also monitored which is used to estimate their limitations to the long-term frequency stability of the ISCAC. The ISCAC was compared with H-maser for 10 days and the Allan deviation went down as 5.4×10-13τ-1/2 from 1 to 10 000 s. It reached 2.6×10-15 at the averaging time of 200 000 s which is mainly limited by the cavity pulling effect.
学科主题	光学工程
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/31130]
专题	中国科学院上海光学精密机械研究所
作者单位	中国科学院上海光学精密机械研究所
推荐引用方式 GB/T 7714	王亚宁. 积分球冷原子钟噪声抑制实验研究[D].

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