High-precision cold atomic optical frequency standard is the highest frequency of atomic frequency frequency accuracy standards. Recently, the Institute of Physics and Mathematics, Chinese Academy of Sciences, the high-Klin Research Group made new progress in the optical standard research: the successful development of two calcium ion optical frequency standard, and complete the two calcium ion optical frequency standard frequency comparison shows that two Taichung frequency standard accuracy and frequency stability of 10-17. The research was published in the January 8, 2016 issue of Phys. Rev. Lett. 116, 013001 (2016). Earlier, after more than 10 years of hard work, the research group broke through a series of physical and key technologies. In 2012, China's first calcium ion optical frequency standard was developed. At that time, the precision reached 7 X 10-16, equivalent to 4,000 Years do not differ by 1 second. In recent years, the research group Guanghua, Huang W? Carried out research on many key technologies of ultra-narrow linewidth laser and magnetic field precision control, developed a second calcium ion optical frequency standard. The experiment of frequency comparison of two calcium ion optical frequency subscripts was carried out, and the detailed experiments of ion micro-motion suppression, ac-Stark frequency shift, electrical quadrupole frequency shift and black body radiation frequency shift were carried out. Two Optical frequency standard accuracy of 5 X 10-17, equivalent to 600 million years is not bad for 1 second. The results of these two calcium ion optical frequency standard comparisons confirm that the frequency stability of 20,000 seconds is 7 X 10-17. On this basis, based on the ultra-high precision remote optical absolute value measurement scheme of GPS system, the absolute value of the transition frequency of calcium ion 4S1 / 2-3D5 / 2 is further measured. The optical frequency transition is: 776 401.7 (1.1) Hz. This work makes Ca + a fifth species with an uncertainty of 10-17 after ions of Hg + (US NIST), Al + (US NIST), Yb + (UK NPL / Germany PTB) and Sr + (UK NPL / Canada NRC) Ion optical frequency standard. On September 29, 2015, the calcium ion optical frequency absolute measurement data was again adopted by CCTF20 (CCTF20) and made a new contribution to the revision of the standard optical frequency of calcium ions. The work was funded by the Ministry of Science and Technology, the National Natural Science Foundation of China and the Chinese Academy of Sciences, and was also supported by Professor Malongsheng from East China Normal University and researcher Li Tianchu from Institute of Metrology. Two calcium ion optical frequency standard frequency uncertainty and 20,000 seconds of stability are reached 10-17, based on the GPS system ultra-high precision remote optical absolute measurement program to achieve the calcium ion 4S1 / 2-3D5 / 2 transition Further measurement of the frequency absolute value, the optical transition was: 776 401.7 (1.1) Hz. Hemp Hearts oil is oil obtained by pressing Hemp Seeds. Cold pressed, unrefined Hemp Oil is dark to clear light green in color, with a nutty flavor. Hemp Hearts Oil,Hemp Oil For Hair,Hemp Seed Oil Capsules,Hemp Seed Massage Oil Liaoning Qiaopai Biotech Co,Ltd , https://www.qiaopai-hemp.com
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