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Improved Evaluation of BBR and Collisional Frequency Shifts of NIM-Sr2 with 7.2 × 10-18 Total Uncertainty 下载免费PDF全文
NIM-Sr2 optical lattice clock has been developed on the Changping campus of National Institute of Metrology(NIM). Considering the limitations in NIM-Sr1, several improved parts have been designed including a differential pumping stage in the vacuum system, a permanent magnet Zeeman slower, water-cooled anti-Helmholtz coils,an extended viewport for Zeeman slower, etc. A clock laser with a short-time stability better than 3 × 10-16 is realized based on a self-designed 30-cm-long ultra-l... 相似文献
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Stable Narrow Linewidth 689nm Diode Laser for the Second Stage Cooling and Trapping of Strontium Atoms 下载免费PDF全文
We report stable narrow linewidth laser systems based on self-developed Littman configuration external cavity diode lasers (ECDLs). The frequency of the ECDL is stabilized to a high fineness ultralow-expansion glass reference cavity with the Pound-Drever-Hall technique. By heterodyne beating of two identical systems, we conclude that the linewidth 4.3× 10^-14 at an averaging measurement time. of each ECDL is reduced to lower than 150 Hz and its frequency stability reaches time of 1 s, the averaged long-term frequency drift is less than 0.2 Hz/s over 30 h 相似文献
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Cold atom clocks have made remarkable progresses in the last two decades and played critical roles in precision measurements. Primary Cs fountain frequency standards have achieved a total uncertainty of a few parts in 1016, and the best optical clock has reached a type B uncertainty below 10-18. Besides applications in the metrology, navigation, etc.,ultra-stable and ultra-accurate atomic clocks have also become powerful tools in the basic scientific investigations. In this paper, we focus on the recent developments in the high-performance cold atomic clocks which can be used as frequency standards to calibrate atomic time scales. The basic principles, performances, and limitations of fountain clocks and optical clocks based on signal trapped ion or neutral atoms are summarized. Their applications in metrology and other areas are briefly introduced. 相似文献
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A Hertz-Linewidth Ultrastable Diode Laser System for Clock Transition Detection of Strontium Atoms 下载免费PDF全文
The frequencies of two 698 nm external cavity diode lasers (ECDLs) are locked separately to two independently located ultrahigh finesse optical resonant cavities with the Pound Drever-Hall technique. The linewidth of each ECDL is measured to be -4.6 Hz by their beating and the fractional frequency stability below 5 × 10^-15 between 1 s to lOs averaging time. Another 698nm laser diode is injection locked to one of the cavity-stabilized ECDLs with a fixed frequency offset for power amplification while maintaining its linewidth and frequency characteristics. The frequency drift is H1 Hz/s measured by a femtosecond optical frequency comb based on erbium fiber. The output of the injection slave laser is delivered to the magneto-optical trap of a Sr optical clock through a iO- ta-long single mode polarization maintaining fiber with an active fiber noise cancelation technique to detect the clock transition of Sr atoms. 相似文献
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光钟能够产生高稳定、高准确的光学频率,在时间频率计量、基础物理研究、相对论大地测量等领域有着潜在的应用。中国光钟研究从21世纪初开始起步,在超稳激光产生、量子参考体系制备、系统频移评估和绝对频率测量等方面取得了长足的进步,目前已经有多个研究组的光钟系统频率不确定度进入10-18量级,多个机构实现了光钟绝对频率测量,并且有三种光钟的测量结果被国际时间频率咨询委员会采纳。文章将回顾中国为应对秒定义变革而开展的高准确度光钟及其绝对频率测量研究,梳理目前取得的进展和成果,总结存在的问题,并对未来发展提出建议。 相似文献
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低噪声微波在冷原子光钟、光子雷达、大科学装置远程同步等领域具有重要的应用价值.本文介绍了一种基于光学-微波相位探测技术的低噪声微波产生方案,利用光纤环路光学-微波鉴相器,将超稳激光的频率稳定度相干传递至介质振荡器.实验采用梳齿相位参考至超稳激光的窄线宽掺铒光纤飞秒光学频率梳,结合光纤环路光学-微波鉴相器和精密锁相装置,将7 GHz介质振荡器同步至光频梳重复频率的高次谐波,同步后的光脉冲序列与微波信号的剩余相位噪声为–100 d Bc/Hz@1 Hz,定时抖动为8.6 fs [1 Hz—1.5 MHz];通过搭建两套低噪声微波产生系统,测得7 GHz微波的剩余相位噪声为–90 d Bc/Hz@1 Hz,对应的频率稳定度为4.8×10–15@1 s.该研究结果对基于光学相干分频的低噪声微波产生提供了一种新思路. 相似文献
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We report the experimental realization of a ^88Sr magneto-optical trap (MOT) operating at the wavelength of 461 nm. The MOT is loaded via a 32 cm long spin-flip type Zeeman slower which enhances the MOT population by a factor of 22. The total laser power available in our experiment is about 300mW. We have trapped 1.6 × 10^8 ^88 Sr atoms with a 679nm and 707nm repumping laser. The two repumping lasers enhance the trap population and trap lifetime by factors of 11 and 7, respectively. The ^88 Sr cloud has a temperature of about 2.3 mK, measured by recording the time evolution of the absorption signal. 相似文献
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A clock laser based on a 30-cm-long ultrahigh finesse optical cavity was developed to improve the frequency stability of the Sr optical lattice clock at the National Institute of Metrology. Using this clock laser to probe the spin-polarized~(87)Sr atoms, a Rabi transition linewidth of 1.8 Hz was obtained with 500 ms interrogation time.Two independent digital servos are used to alternatively lock the clock laser to the ~1S_0(m_F=+9∕2)→~3P_0(m_F=+9∕2)transition. The Allan deviation shows that the short-term frequency stability is better than3.2 × 10~(-16)and averages down followed by 1.8 × 10~(-15)∕τ~(1/2). 相似文献
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