“Cold” Atoms

L. Holler, Gerald Auböck, C. Binder +3 more

In the performed experiment we trap simultaneously in the Magneto-Optical Trap cold atoms of 7Li with cold sodium atoms and cold 6Li atoms with cold 23Na atoms. We investigated in detail heteronuclear interactions between cold isotopes of lithium atoms and cold sodium atoms in presence of the laser light.

Tapio Simula

Junru Shi, Xinliang Wang, Yong Guan +8 more

The Gaussian radius and temperature of cold atomic cloud are important parameters in describing the state of cold atoms. The precise measuring of these two parameters is of great significance for studying the cold atoms. In this paper, we propose a new method named knife-edge to measure the Gaussian radius and temperature of the cold atomic cloud. A near-resonant and supersaturated laser beam, whose size is controlled by a knife-edge aperture, is used to push away the cold atoms in the free falling process of cold atomic cloud. By detecting the intensity of fluorescence signal, the numbers of residual atoms under different-sized near-resonant beams can be obtained. According to the characteristic of cold atoms′ distribution, we construct a theoretical model to derive the Gaussian radius of cold atomic cloud from the recorded residual atom number and near-resonant beam size. Since the Gaussian radius and temperature of cold atomic cloud are associated with each other, we can finally obtain the temperature of cold atomic cloud through the recorded residual atom number and beam size. By using this method, we successfully measure the Gaussian radii of cold atomic cloud at the heights of 10 mm and 160 mm below the center of 3D-MOT (three dimensional magneto-optical trap) to be (1.54 ± 0.05) mm and (3.29 ± 0.08) mm, respectively. The corresponding temperature of cold atomic cloud is calculated to be (7.50 ± 0.49) μK, which is well consistent with the experimental result obtained by using the time-of-flight method under the same condition. This experiment is conducted on the platform of Cesium atomic fountain clock of National Time Service Center, China.

Xinchuan Ouyang, Bowen Yang, Jianliao Deng +5 more

We propose a simple pumping method to increase the effective population of cold atoms in the clock state and investigate the factors which affect the pumping efficiency in cold atom systems. We report the theory and demonstrate the corresponding experiment in an 87Rb integrating sphere cold atom clock. The experimental results show that the population of cold atoms in the Zeeman sublevel |F = 2, mF = 0〉 is approximately 1.62 times that of the result using optical pumping alone. This method can also be applied to increase the effective population in any one of the target Zeeman sublevels in other cold atom systems.