A laser cooled cesium atomic fountain: towards a high performance clock.

Ch Salomon, Brahim Lounis, Jakob Reichel +3 more

Jiang Chen, Rui Lin, Dandan Liu +5 more

The quality of the cold atoms sample plays an important role to improve the performance of cesium atomic fountain clocks. The preparation of cold atoms sample has a strict requirement for cooling lasers characteristics such as power stability, polarization, collimation, uniformity and verticality. This work implements a design of an expander system of high stable laser beam for the cold atom preparation. The cooling laser characteristics can be adjusted by the design, and the use of non-magnetic materials to avoid the magnetic field on the impact of cold atom. The cold atom sample with the number of 2×108 and temperature of 5μk was obtained by expander system. The result meets the requirements of the preparation of cold atoms for cesium atomic fountain clocks.

Yimin Li, Jidong Hou, Junxian Fu +3 more

Cesium atomic fountain clock is the quantum frequency standard with very high accuracy. Research on laser cooling and trapping of cesium atom at Peking University began in 1993. A cesium atomic fountain frequency standard is being developed. A magneto-optical trap with some 108 trapped atoms and an optical molasses with the cold atoms of the temperature of 10/spl mu/K have been achieved previously. The device has been carefully designed and is under construction. It is composed of two main parts: vacuum system and laser system. The article describes the apparatus and presents a brief introduction to some considerations on the atomic clock.

David W. Sesko, Carl Wieman

William M. Klipstein, Christopher R. Ekstrom, S. L. Rolston +1 more

We report here on progress towards the realization of an atomic frequency standard using a fountain of laser cooled cesium atoms. We have recently observed Ramsey fringes on the 9.2 GHz clock transition and have begun preliminary work aimed at characterizing our fountain. This paper describes briefly the apparatus, discusses our current work and near-term directions. We conclude with a brief discussion of a laser system being built to realize two-dimensional Raman cooling or Raman velocity selection for cooling below the single photon recoil limit. This system will be used either in our fountain or in a cold-atom clock to be flown on the International Space Station.

Kurt Gibble