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Laser cooling and trapping of ytterbium atoms
Xin-ye XU (徐信业), Wen-li WANG (王文丽), Qing-hong ZHOU (周庆红), Guo-hui LI (李国辉), Hai-ling JIANG (蒋海灵), Lin-fang CHEN (陈林芳), Jie YE (叶捷), Zhi-hong ZHOU (周志红), Yin CAI (蔡寅), Hai-yao TANG (唐海瑶), Min ZHOU (周敏)
Front Phys Chin. 2009, 4 (2 ): 160-164.
https://doi.org/10.1007/s11467-009-0033-7
The experiments on the laser cooling and trapping of ytterbium atoms are reported, including the two-dimensional transversal cooling, longitudinal velocity Zeeman deceleration, and a magneto-optical trap with a broadband transition at a wavelength of 399 nm. The magnetic field distributions along the axis of a Zeeman slower were measured and in a good agreement with the calculated results. Cold ytterbium atoms were produced with a number of about 107 and a temperature of a few milli-Kelvin. In addition, using a 556-nm laser, the excitations of cold ytterbium atoms at 1 S0 -3 P1 transition were observed. The ytterbium atoms will be further cooled in a 556-nm magneto-optical trap and loaded into a three-dimensional optical lattice to make an ytterbium optical clock.
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Experimental progress in gravity measurement with an atom interferometer
Min-kang ZHOU (周敏康), Zhong-kun HU (胡忠坤), Xiao-chun DUAN (段小春), Bu-liang SUN (孙布梁), Jin-bo ZHAO (赵锦波), Jun LUO (罗俊)
Front Phys Chin. 2009, 4 (2 ): 170-173.
https://doi.org/10.1007/s11467-009-0036-4
Precisely determining gravity acceleration g plays an important role on both geophysics and metrology. For gravity measurements and high-precision gravitation experiments, a cold atom gravimeter with the aimed resolution of 10-9 g/Hz1/2 (1 g =9.8 m/s2 ) is being built in our cave laboratory. There will be four steps for our 87 Rb atom gravimeter, Magneto–Optical Trap (MOT) for cooling and trapping atoms, initial state preparation, π/2-π-π/2 Raman laser pulse interactions with cold atoms, and the final state detection for phase measurement. About 108 atoms have been trapped by our MOT and further cooled by moving molasses, and an atomic fountain has also been observed.
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Experimental progress in optical manipulation of single atoms for cavity QED
Yu-chi ZHANG (张玉驰), Gang LI (李刚), Peng-fei ZHANG (张鹏飞), Jun-min WANG (王军民), Tian-cai ZHANG (张天才)
Front Phys Chin. 2009, 4 (2 ): 190-197.
https://doi.org/10.1007/s11467-009-0016-8
Cavity QED, as a fundamental system and research field, not only illuminates the primary aspects of decoherence and coherence in quantum dynamics, but also advances quantum information science. Manipulation of single atoms, in the context of cavity QED, is the essential element and has been becoming a hot issue for the past two decades. In this review paper, we will concentrate on the experimental aspects for manipulating the neutral atoms strongly coupled to a high-finesse cavity in the optical regime, including atomic cooling and trapping, different configurations of atom transportation and the wide variety of quantum outgrowths based on cavity QED, such as one atom laser, single photon source, etc. The cavity QED system at Shanxi University is briefly introduced.
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Condensation and evolution of a space–time network
Qiao BI (毕桥), Li-li LIU(刘莉丽), Jin-qing FANG(方锦清)
Front Phys Chin. 2009, 4 (2 ): 231-234.
https://doi.org/10.1007/s11467-009-0049-z
In this work, we try to propose in a novel way, using the Bose and Fermi quantum network approach, a framework studying condensation and evolution of a space–time network described by the Loop quantum gravity. Considering quantum network connectivity features in Loop quantum gravity, we introduce a link operator, and through extending the dynamical equation for the evolution of the quantum network posed by Ginestra Bianconi to an operator equation, we get the solution of the link operator. This solution is relevant to the Hamiltonian of the network, and then is related to the energy distribution of network nodes. Showing that tremendous energy distribution induces a huge curved space–time network may indicate space time condensation in high-energy nodes. For example, in the case of black holes, quantum energy distribution is related to the area, thus the eigenvalues of the link operator of the nodes can be related to the quantum number of the area, and the eigenvectors are just the spin network states. This reveals that the degree distribution of nodes for the space–time network is quantized, which can form space–time network condensation. The black hole is a sort of result of space–time network condensation, however there may be more extensive space–time network condensations, such as the universe singularity (big bang).
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