Content of TOPICAL REVIEW—Ultracold atom and its application in precision measurement in our journal

Published in last 1 year |  In last 2 years |  In last 3 years |  All Please wait a minute... For selected: Download citations EndNote Ris BibTeX Toggle thumbnails Select Cold atom clocks and their applications in precision measurements Shao-Yang Dai(戴少阳), Fa-Song Zheng(郑发松), Kun Liu(刘昆), Wei-Liang Chen(陈伟亮), Yi-Ge Lin(林弋戈), Tian-Chu Li(李天初), and Fang Fang(房芳) Chin. Phys. B, 2021, 30 (1): 013701.   DOI: 10.1088/1674-1056/abbbee Abstract （600）   HTML （11）    PDF （3844KB）（498）       Knowledge map    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. Select Improve the performance of interferometer with ultra-cold atoms Xiangyu Dong(董翔宇), Shengjie Jin(金圣杰), Hongmian Shui(税鸿冕), Peng Peng(彭鹏), and Xiaoji Zhou(周小计) Chin. Phys. B, 2021, 30 (1): 014210.   DOI: 10.1088/1674-1056/abcf33 Abstract （594）   HTML （4）    PDF （3289KB）（317）       Knowledge map    Ultra-cold atoms provide ideal platforms for interferometry. The macroscopic matter-wave property of ultra-cold atoms leads to large coherent length and long coherent time, which enable high accuracy and sensitivity to measurement. Here, we review our efforts to improve the performance of the interferometer. We demonstrate a shortcut method for manipulating ultra-cold atoms in an optical lattice. Compared with traditional ones, this shortcut method can reduce the manipulation time by up to three orders of magnitude. We construct a matter-wave Ramsey interferometer for trapped motional quantum states and significantly increase its coherence time by one order of magnitude with an echo technique based on this method. Efforts have also been made to enhance the resolution by multimode scheme. Application of a noise-resilient multi-component interferometer shows that increasing the number of paths could sharpen the peaks in the time-domain interference fringes, which leads to a resolution nearly twice compared with that of a conventional double-path two-mode interferometer. With the shortcut method mentioned above, improvement of the momentum resolution could also be fulfilled, which leads to atomic momentum patterns less than 0.6 \(\hbar k_L\). To identify and remove systematic noises, we introduce the methods based on the principal component analysis (PCA) that reduce the noise in detection close to the \(1/\sqrt2\) of the photon-shot noise and separate and identify or even eliminate noises. Furthermore, we give a proposal to measure precisely the local gravity acceleration within a few centimeters based on our study of ultracold atoms in precision measurements. Select Precision measurements with cold atoms and trapped ions Qiuxin Zhang(张球新), Yirong Wang(王艺蓉), Chenhao Zhu(朱晨昊), Yuxin Wang(王玉欣), Xiang Zhang(张翔), Kuiyi Gao(高奎意), Wei Zhang(张威) Chin. Phys. B, 2020, 29 (9): 093203.   DOI: 10.1088/1674-1056/aba9c6 Abstract （901）   HTML    PDF （3016KB）（232）       Knowledge map    Recent progresses on quantum control of cold atoms and trapped ions in both the scientific and technological aspects greatly advance the applications in precision measurement. Thanks to the exceptional controllability and versatility of these massive quantum systems, unprecedented sensitivity has been achieved in clocks, magnetometers, and interferometers based on cold atoms and ions. Besides, these systems also feature many characteristics that can be employed to facilitate the applications in different scenarios. In this review, we briefly introduce the principles of optical clocks, cold atom magnetometers, and atom interferometers used for precision measurement of time, magnetic field, and inertial forces. The main content is then devoted to summarize some recent experimental and theoretical progresses in these three applications, with special attention being paid to the new designs and possibilities towards better performance. The purpose of this review is by no means to give a complete overview of all important works in this fast developing field, but to draw a rough sketch about the frontiers and show the fascinating future lying ahead. Select Movable precision gravimeters based on cold atom interferometry Jiong-Yang Zhang(张炯阳), Le-Le Chen(陈乐乐), Yuan Cheng(程源), Qin Luo(罗覃), Yu-Biao Shu(舒玉彪), Xiao-Chun Duan(段小春), Min-Kang Zhou(周敏康), Zhong-Kun Hu(胡忠坤) Chin. Phys. B, 2020, 29 (9): 093702.   DOI: 10.1088/1674-1056/aba9bc Abstract （685）   HTML    PDF （2115KB）（281）       Knowledge map    High precision atom interferometers have shown attractive prospects in laboratory for testing fundamental physics and inertial sensing. Efforts on applying this innovative technology to field applications are also being made intensively. As the manipulation of cold atoms and related matching technologies mature, inertial sensors based on atom interferometry can be adapted to various indoor or mobile platforms. A series of experiments have been conducted and high performance has been achieved. In this paper, we will introduce the principles, the key technologies, and the applications of atom interferometers, and mainly review the recent progress of movable atom gravimeters. Select Progress on the 40Ca+ ion optical clock Baolin Zhang(张宝林), Yao Huang(黄垚), Huaqing Zhang(张华青), Yanmei Hao(郝艳梅), Mengyan Zeng(曾孟彦), Hua Guan(管桦), Kelin Gao(高克林) Chin. Phys. B, 2020, 29 (7): 074209.   DOI: 10.1088/1674-1056/ab9432 Abstract （851）   HTML    PDF （1696KB）（233）       Knowledge map    Progress of the 40Ca+ ion optical clock based on the 42S1/2-3d 2D5/2 electric quadrupole transition is reported. By setting the drive frequency to the “magic” frequency Ω0, the frequency uncertainty caused by the scalar Stark shift and second-order Doppler shift induced by micromotion is reduced to the 10-19 level. By precisely measuring the differential static scalar polarizability △α0, the uncertainty due to the blackbody radiation (BBR) shift (coefficient) is reduced to the 10-19 level. With the help of a second-order integrating servo algorithm, the uncertainty due to the servo error is reduced to the 10-18 level. The total fractional uncertainty of the 40Ca+ ion optical clock is then improved to 2.2×10-17, whereas this value is mainly restricted by the uncertainty of the BBR shift due to temperature fluctuations. The state preparation is introduced together with improvements in the pulse sequence, and furthermore, a better signal to noise ratio (SNR) and less dead time are achieved. The clock stability of a single clock is improved to 4.8×10-15/√τ (in seconds).